Buttercream cupcakes

Tips for Extreme Weather Cake Decorators: Fillings & Frostings

When we speak about extreme weather conditions, we refer to extreme cold, heat, and heat & humidity.

Fortunately, once fillings and frostings are made and used in a cake, the cold will not affect them. In fact, it will keep everything in place; providing cakes are not allowed to freeze if they are being transported to a venue.

The extreme heat and heat plus humidity will try to be your worst enemy, but there are recipes you can use that will put the risk of your cake being spoiled to the minimum.

If you spend hours decorating a beautiful cake, it can be devastating if extreme weather conditions destroy all your hard work, so I pass on some recipes and tips that may help you.

For the majority of my cake making and decorating career, I lived in England, where it seldom gets very hot or too cold, and I never noticed if it was humid or not. However, since moving to central Europe several years ago, where it can drop to -15C/5F in the winter and rise to over 40C/104F in the summer and the humidity can fluctuate, I am now experiencing some of the issues that are everyday problems for many people.

Since living here, I have used fillings and frosting in the summer to withstand heat and humidity. However, I have found that venues seem well prepared for most weather conditions, so I can honestly say that I have not been able to test them properly.

That was until…


Last year I made a two-tiered cake as a gift for a friend for a birthday celebration in August that I also attended. When August came around, we were in the middle of an extreme heatwave, so I knew that I had to choose fillings and icing that would be less likely to melt.

Because it was left up to me to choose how to present the cakes, I chose to use a cake stand that displayed the cakes individually rather than stack them.

I chose to present it that way because the weight of a heavy cake resting on another cake, filled with buttercream or something similar, can be a recipe for disaster in hot weather.

I also used three dowels in each cake, so there would be no chance of the layers slipping. It may have been overkill, especially as the cakes were not going to be stacked, but as I was going to be at the party, I wanted to be as sure as I could that I couldn’t present a crooked cake.

By the time I set off to the venue, I had become paranoid, as I had visions of it melting on the way, so I packed each tier separately, with plenty of ice packs in the bottom of each box. I even took a fan with me in case the venue wasn’t appropriately air-conditioned.

Upon arrival, before I unloaded the cake, I was taken to where it was to be displayed.

To my horror, the party was to be held in a garden. The cake was to be put on a table outside, in direct sunlight. Admittedly, it was 5 pm, but it was still 30 C, and there was also some humidity.

Secretly I was panicking. Should I make a fuss in front of all the people standing around waiting for me to put up the cake and demand an air-conditioned place to put it, or should I pretend everything was OK?

I may have been wrong, but I decided to go ahead and put it where they wanted it, so I carried on as if everything was just as it should be, set the cake up, walked away, and joined in the party and what a great party it was.

I tried not to look at the cake during the evening and just kept my fingers crossed that I had chosen the right fillings, etc., that wouldn’t melt and that my creation wouldn’t ruin the party.

I held my breath and cut the cake…


Three hours later, I was asked to cut the cakes. I could feel myself panicking again, but it didn’t look as if they had moved. What was I going to do if the inside of the cake was a big melted mess?

The guests gathered around to watch me cut the cakes, and you cannot imagine the relief when I cut into them, and they were just perfect.

The bottom tier was a 28cm /11”,  three-layered vanilla sponge filled with homemade lemon curd and ermine lemon buttercream, crumb coated in ermine buttercream and covered in lemon-flavored rolled fondant.

The top tier was a 20cm/8” dark chocolate, three-layered cake, filled with dark chocolate whipped ganache, crumb coated with unwhipped dark chocolate ganache, and covered with rolled fondant.

I had never used Ermine buttercream before, and to tell you the truth, when a friend suggested I use it, I wasn’t keen on making it. Some people call it flour buttercream or cooked milk buttercream, and I couldn’t see how that would be nice in a cake, but I was assured by the friend who gave me the recipe that it tastes good and is stable in heat and humidity.

I did a test batch the week before I need it for the cake, and I was amazed at the result. It was the creamiest, smoothest buttercream I had ever tasted. I have been using it ever since, even throughout the winter, because it is good, everyone likes it, and it did live up to its reputation of being stable in heat and humidity.

I used lactose-free butter and lactose-free milk in my ermine buttercream because I am intolerant to lactose, and so were several of the party guests, and it worked perfectly.

Ermine Buttercream



30g1½ ozCornflour/cornstarch
30g1½ ozAll-purpose Flour
300g10½ ozGranulated Sugar
355 ml1.5 cups/12 fl ozMilk
¼ tsp Salt
½ tsp Vanilla or lemon extract (or to own taste)
340g Butter – soft but not melted


  1. You will need a medium-sized saucepan and a bowl that is bigger than the pan.
  2. Put some cold water in the bowl and set to one side. This is used to begin the cooling process once the mixture is cooked.
  3. In a bowl, combine the cornflour/cornstarch, flour, milk, and salt. Stir until they are all mixed, smoothly.
  4. Pour the mixture through a fine sieve into the pan, then add the sugar.
  5. Cook the mixture over medium heat, continually stirring until it thickens and comes to a boil, then turn the heat right down, and still stirring, simmer for 2 minutes.
  6. Take the pan off the heat and place in the bowl of cold water, making sure not to get any of the cold water into the mixture in the pan, keep gently stirring for two minutes.
  7. Remove the pan from the bowl of water and wipe the bottom dry.
  8. Empty the pan’s contents into a stand mixer bowl or the bowl you will use with a hand mixer.
  9. Place a piece of cling film/plastic wrap directly onto the mixture in the bowl, making sure there is no space for air to get to it.
  10. Leave until the mixture has dropped to room temperature.
  11. Once the mixture has reached room temperature, add the vanilla or lemon extract and slowly whisk until combined.
  12. Add the soft butter a spoonful at a time, slowly whisking between additions, until it has all been added.
  13. Turn the mixer up to medium speed and whisk for 5 mins until the buttercream is light and fluffy.
  14. Cover and leave to stand at room temperature for about 1 hour to thicken.

For chocolate-flavored ermine, buttercream, add three tablespoons unsweetened cocoa powder to the milk mixture at the start of the process and leave out the vanilla or lemon extract.


Chocolate Ganache is so good…


If you are a chocoholic, like I am, and dark chocolate is your favorite, then there’s nothing better than a dark chocolate cake filled with dark chocolate whipped ganache and covered with dark, unwhipped chocolate ganache.

My experience of ganache staying stable in the heat may have been because I covered it with rolling fondant. However, chocolate ganache made with high-quality dark chocolate (75%-80% cocoa) should be stable up to 85F/30C, so my cake may have been just within the melting point.

If you are going to make a chocolate ganache for decorating a cake in a hot/humid situation, then using white chocolate is not a good idea. White chocolate is a by-product of the chocolate-making process and is made using cocoa butter, milk, sugar, and some flavoring, so it is more like candy.

Milk chocolate can have as little as 10% cocoa and is mixed with milk and other ingredients, so that doesn’t stand up very well in the heat either.

Whipped or not whipped…


Whipped ganache can be used for filling a cake, covering a cake, and for piping. Ganache that is not whipped is used as a frosting to coat a cake, as a filling between layers, and for crumb coating a cake,

The proportions of chocolate and cream used for ganache are based on weight, and for my cake that got left in the sun, I used a 2-1 ratio, which means I had double the weight of chocolate to cream, e.g., 227g/8 oz chocolate to 114g/ 4 oz cream.

Under normal circumstances (not so much heat/humidity), I would use a 1:1 ratio – equal parts chocolate and cream – which makes a softer ganache.

Chocolate Ganache



heavy/double cream  (or 30% fat lactose-free cream)

75% good quality plain chocolate

The quantities in the table below will be enough for filling for a three-layer cake and a crumb coat or a filling for a two-layer cake and an all-over frosting coat


Round Cake


Square Cake

SizeDark ChocolateHeavy/Double Cream  Dark ChocolateHeavy/Double Cream
6”/15cm350g/12 oz175ml/6 fl oz 450g/16 oz225ml/8 fl oz
7”/18cm450g/16 oz225ml/8 fl oz 575g/20 oz288ml/10 fl oz
8”/20cm575g/20 oz288ml/10 fl oz 700g/24 oz350ml/12 fl oz
9”/22.5cm650g/23 oz325ml/11 fl oz 825g/28 oz412ml/14  fl oz
10”/26cm775g/27 oz388ml/13.5 fl oz 975g/34 oz488ml/17 fl oz
11”/28cm900g/31 oz450ml/15.5 fl oz 1130g/40 oz565ml/20 fl oz
12”/30cm1025g/36 oz512ml/18 fl oz 1325g/46 oz676ml/23 fl oz

Note: Use a larger pan than your gas or electric ring, so you don’t scorch the cream.


  1. Break the chocolate into small pieces and place in a bowl
  2. Put the cream into a pan and, on medium, heat brings it to just below boiling point.
  3. Pour the cream over the chocolate and leave for a few minutes until the chocolate has melted.
  4. Stir the mixture
  5. It may look as if it won’t combine properly at first but keep stirring, and it will blend together.
  6. Taste the mixture and if it is not sweet enough, add some icing/confectioners sugar a teaspoon at a time and make sure it has melted. Very little sugar will sweeten the mixture, so don’t add too much, or you will ruin the ganache’s consistency.
  7. Leave to cool

To spread the ganache over a cake, it needs to be still slightly warm to pour it but thick enough to stay on the cake.

If you whip the ganache, let it cool until thick, then beat until light and fluffy about 2-3 mins, but be careful not to overbeat.

Another buttercream…


This buttercream also holds up quite well in humid/hot weather conditions.

Swiss/Mousseline Buttercream


All ingredients need to be at room temperature.

Use a sugar thermometer to measure the temperature of the sugar syrup.


454g16ozButter – soft but not melted
5 large Egg whites
200g7ozGranulated sugar
½ tsp Cream of Tartar
¼ cup  Water
½ tsp  Vanilla extract


  1. Whisk the butter until smooth and creamy
  2. Place 150g/4½oz sugar and ¼ cup water in a saucepan that is wider than the burner
  3. Heat mixture, while stirring,  until the sugar has melted (brushing the crystals of sugar down the inside of the pan with a brush dipped in cold water).
  4. Once melted, stop stirring & remove from heat, and set aside.
  5. Put some cold water in a bowl that is bigger than the bottom of the saucepan and set aside.
  6. Place the egg whites and the cream of tartar in the bowl of a stand mixer and, using a whisk attachment, whisk until soft peak stage.
  7. Stir in the remaining sugar, then whisk until it reaches the stiff peak stage.
  8. Return the pan with the syrup to the heat and boil until it reaches 120C/248F on the sugar thermometer, the softball toffee stage.
  9. Plunge the bottom of the pan into the bowl of cold water to stop the cooking process.
  10. Make sure you don’t get any water into the toffee.
  11. Leave in the water for 1 minute.
  12. With the mixer running on high speed, slowly pour the toffee, in a thin stream, onto the egg whites. Be careful not to let the stream of toffee touch the mixer blade, or you will have lumps of toffee in your buttercream.
  13. Once all the toffee has been incorporated into the egg whites, lower the mixer’s speed to medium and beat until the bowl feels cool.
  14. Beat in the butter, one spoonful at a time (it may seem thinner at first but will thicken by the time it is all added)

This buttercream will keep for up to 5 days, covered, in the fridge, or it can be frozen.

Before using, bring to room temperature and re-beat.

The trick is to test it…


There is no guarantee that these fillings and frosting will stand up to your particular climate, and I can only emphasize the fact that you must try them out before you either make a cake for a special occasion or make a cake to sell.

Don’t try them out on a dummy cake because the cake itself will contribute to toppings or fillings’ stability.

Testing your product takes a bit of effort, but it will save a lot of disappointment.

Gum paste flowers and rolling fondant…


In my blog post about making Gum Paste Sugar Flowers in extreme weather conditions, you will find lots of tips and information that I am sure you will find useful.

In my blog post about using Rolling Fondant in extreme weather conditions, you will find lots of useful tips and information.

If you have any questions about frostings and fillings in extreme weather conditions, please ask them in the comments box below, and I will do my best to answer them.

If you have any tried and tested recipes you know will stand up to extreme weather conditions, please share them in the comments box as I am always ready to learn.

Joyce Freeman

Joyce Freeman

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6 thoughts on “Tips for Extreme Weather Cake Decorators: Fillings & Frostings”

    1. Hi Norma,
      Thank you for your comment.
      I have not made a custard pear pie myself but I have made pies with just a custard filling.
      You can freeze them but when they thaw the custard is often watery so it is not something I would recommend.
      That sort of pie is best eaten freshly made.
      You can find more information about freezing pies on the following website
      Having said all that, I think that your custard pear pie sounds delicious and I will have a go at making one.
      Best wishes

  1. Hi Joyce,
    I tried the ermine buttercream today and it was super smooth but a bit too sweet. I therefore added 3 tablespoon cocoa powder to make it chocolate buttercream. Will cut back on the sugar next time and see how it turns out. I think this will be my go to buttercream. Thanks for sharing the recipe!!

    1. Hi Barbs,
      When I use a new buttercream recipe it always takes me a couple of times making it to get the sweetness balance just right.
      It will also depend on what I flavor it with so it’s advisable to add the sugar gradually and taste between each addition.
      When I flavor it with fresh lemons it needs more sugar than with a less strong flavor.
      Full marks to you for being able to adapt the sweet batch you made into chocolate buttercream.
      In all the years I have been making cakes it was not until recently that I found out about ermine buttercream.
      I must admit when I realised it was a cooked buttercream I couldn’t imagine it being very nice at all.
      However, being one to experiment I made some, and I was absolutely blown away by how amazing it is, and I use it frequently now.
      I have a request for a lemon cake again this coming weekend and I am about to make some lemon curd to spread below my lemon ermine buttercream.
      Best wishes,

  2. Hi Joyce!
    I’m gonna try your fondant recipe for the first time. Will surely post a comment on how it turns out. Would like to know if I can use ermine buttercream underneath the rolled fondant? Or would chocolate ganache be a better option.

    1. Hi Nikita,
      I am pleased that you are going to make some fondant from the recipe. I have just completed a large batch ready for my Christmas cakes.

      Last week, I made a vanilla cake, cut it in half, and spread the center with a layer of home-made lemon curd and then a Lemon Ermine Buttercream layer. I covered the whole cake with lemon Ermine Buttercream and then covered it all with rolled fondant. It was delicious.

      I often use chocolate ganache under rolled fondant, and that is equally delicious. If you have downloaded the free eBooks from this site, I can recommend the Dark Chocolate Cake from the recipe book. It is one I use all the time. It takes a bit of fiddling about to make it, but for me, it’s one that never fails.

      Let me know how you get on.
      Best wishes

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