This Summer, something happened to me that has never happened before (to my knowledge at least): one of my cakes melted in the outdoor heat. I made a birthday cake for a dear friend’s daughter – my vegan vanilla cake with vegan vanilla buttercream. The party was outdoors and the temperature was around 85 degrees. I refrigerated the cake up until I needed to drive it to the party, thinking that would be enough to preserve it for a few hours. But about an hour after the cake was displayed, the thing started melting (along with my heart). Thankfully, these were the kind of friends who were able to laugh about it with me as it all fell apart. Here’s a before and after:
Although it was a first for me, it got me thinking about so many of you who live in hot and humid climates. I’ve even gotten questions over the years from said people wondering how to make their buttercream more heat stable. The fact of the matter is, the butter in buttercream frosting starts to break down when it’s in an environment that’s above 82 degrees, and vegan butter has an even lower melting point. So, I thought I’d do some experimenting on how to add stability to your buttercream (both vegan and non) for those hot and humid days while keeping your frosting nice and tasty.
For my experiment, I created four mini cakes and frosted them each with different frostings using my favorite vanilla buttercream recipe as a base:
- All butter (aka the recipe as-is)
- Half butter and half shortening
- Half butter and half shortening + meringue powder for added stability
- Half vegan butter and half shortening (with coconut milk as the liquid)
I refrigerated each cake until firm before placing them in the direct sun on an 88 degree day with 35% humidity and here’s a video of what happened:
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Buttercream Heat Test Results
Over the course of the two hours I had the cakes in the sun, none of them completely melted, which was kind of disappointing because I wanted things to be more dramatic. The day just wasn’t hot enough. So in the end, I had to break out the hair dryer to see what would happen with more heat applied.
After I cranked up the heat on these cakes, the all-butter buttercream frosted cake melted into soup:
The cake with the half vegan butter and half shortening got a huge air bubble in the frosting that started to melt:
The half butter and half shortening frosted cake looked pretty good after one hour but this is after two hours out in the direct sun + hair dryer:
And the half butter/half shortening with added meringue powder had relatively no change:
I did try an all-shortening frosting because I hear that’s really heat stable, but just couldn’t get over how terrible it tasted. You’d have to use a lot of flavoring to get it to taste normal (and even then, the texture is a little weird).
I concluded that when you’re up against crazy heat (according to these test results at least), use half butter and half shortening with meringue powder. If you’re in need of vegan frosting, you can chance it with half vegan butter and half shortening or try the all-shortening route (with the meringue powder omitted) if you can get it to taste good. I’m going to add my preferred recipe below and in the notes, I will show you how to adapt the recipe for using all-shortening, making it vegan, etc.
What is High Ratio Shortening?
When you think of shortening, what do you think of? Crisco is what I thought of before all my research into heat stable buttercream. It turns out that Crisco (and most shortening) is made with zero trans fat – in other words, it won’t add enough stability to your frosting. So in order to add that stability, you need what’s called high ratio shortening (sometimes called icing shortening). High ratio shortening has a high ratio of fat with added emulsifiers and no added salt or water. In other words, the micro emulsifiers in it help your frosting to hold more sugar and liquid and thus make it more temperature resistant.
Unlike Crisco though, high ratio shortening can’t be found at your typical grocery store. I found this high ratio shortening on Amazon,, but there are other brands that cake decorators use (see the list below). You might be lucky and live close to a cake decorating shop that sells high ratio shortening, so check your local area to see. If you can’t find it locally, here are some links to online cake shops I’ve collected (not sponsored):
- Sweetex High Ratio Shortening
- Alpine High Ratio Shortening
- Bake Supply High Ratio Shortening
- Oasis High Ratio Shortening
What is Meringue Powder?
Meringue powder is basically powdered egg whites, but it also contains cornstarch, sugar for sweetness, gum arabic for thickening, and cream of tartar which helps with stabilizing. If you want to try just adding meringue powder to your buttercream without adding any shortening, add 1 Tbsp (per batch of frosting) by mixing it into the powdered sugar before adding it to the butter in the linked recipe.
With taste and stability in mind, here’s my new go-to recipe for heat stable buttercream:
Heat Stable Vanilla Buttercream
Ingredients
- 1/2 Cup (113g) unsalted butter, room temperature
- 1/2 Cup (100g) high ratio shortening*
- 3 1/2 Cups (420g) powdered sugar
- 1 Tbsp meringue powder
- 2 tsp vanilla extract
- 2 Tbsp whole milk or heavy whipping cream, room temperature
- 1/4 tsp salt, or to taste
Instructions
- With a hand mixer or paddle attachment on your stand mixer, cream the butter and shortening on medium-high until it’s creamy and light (almost white) in color. About 7 minutes.
- Whisk the meringue powder into the powdered sugar. Then, with the mixer on low, add the meringue/powdered sugar mixture one cup at a time, scraping down after each addition and making sure each cup is fully incorporated before adding the next one.
- Add vanilla, milk, and salt and mix on low for another minute until fully incorporated.
Notes
- Frost 12-15 cupcakes with a piping bag
- Fill and crumb coat a three-layer 6-inch cake or two-layer 8-inch cake. To have enough for frosting and decorating as well, double the recipe.
Did you try this recipe? I want to know that you think! Let me know in the comments below or feel free to tag @sugarandsparrowco on Instagram and show me. I love to see what you create! And if you have a go-to recipe for heat stable buttercream or technique that you swear by, let us all know in the comments. We’re all in this together!
Would cream of tartar hold up the frosting?
Hi Richie! I haven’t experimented with cream of tartar but it sounds like it could be a good stabilizer! Let me know if you try it.
Just made this recipe and I am extremely happy with it. It tastes great and I put it next to my heated oven for about a half hour and no changes in it’s form. Can the recipe be doubled or even tripled?
That’s amazing, Angel! I’m so happy this recipe was a hit! It can absolutely be doubled, tripled, and scaled up any way you want!
Hi Whitney, can I do butter, meringue powder and all vegetable shortening as an alternative to HRS? thanks so much
Hi Norma! Yes, if you can’t find high ratio shortening then all-vegetable shortening and meringue powder should work to stabilize against the heat. If you can find HRS, that will be your most heat stable option.
Can I add anything to this after it’s made? I’d like to make this but add marshmallow fluff to it.
Hi Dulce! I have never done that before, but you are welcome to try it. Since marshmallow fluff is so sweet I would recommend reducing the powdered sugar if you do add it.
Hi Whitney!
I am unable to find HRS in my country.
In a previous comment you had mentioned using all butter and meringue powder.
Does that mean adding an additional 100g of butter(the quantity of HRS in the recipe is 100g)?
And if so, what are the changes in the quantity of meringue powder?
Thank you!
Hi Shreeya! If using all butter, you’ll want to add an additional 113g of butter (it weighs a little more than shortening) and add 1 Tbsp of meringue powder per batch. Just to clarify, this won’t be as heat stable as using HRS, so if this is for an important event I would do some experimenting first.
Hello I just saw the recepie and its good for what i am looking for. I have been searching for a recipe like this for my wedding cake. I am asking to see what the rations or measurements for a wedding cake for 100 people. how much will i have to make for a two tear cake size 12″ and 9″ cakes with fillings.
Yay, Guadalupe! I hope you love this recipe and congratulations on your wedding. To fill and frost a two tiered cake of that size, I would make 5-6x the recipe. Hope that helps!
Thank you so much for this recipe! I used it for my 3 tier wedding cake (subbing a little almond extract for vanilla and adding a little purple gel color to make it a crisp white), and it held up super well outdoors in August. Delicious, too!
Yay, Jess! I am so happy it was a hit and worked so well for the August heat!
Hello,
What would I need to do if I wanted to add chocolate.
Hi Sonya! To make a chocolate version, use this chocolate buttercream recipe and sub half the butter with high ratio shortening + add 1 Tbsp meringue powder: https://sugarandsparrow.com/chocolate-buttercream-recipe/
Hello, I made the frosting last night for a test for son’s upcoming wedding and it tasted great. I stored in airtight container overnight in the fridge, and brought it to room temp today and tried to re whip in mixer and the entire thing turned to liquid. Was I only supposed to hand stir instead of using the mixer or what went wrong. Really want to use the recipe but now scared as won’t have time to make new if happens again. Thank you
Hi Carey! That is really strange. Did you substitute anything or change any amounts? And how warm was it in your kitchen when you were bringing it to room temp?
Hi, I followed the recipe exactly with no substitutions; used sweetex shortening; kitchen is set at 72. I need to make the frosting tonight ao can decorate the cake tomorrow. Should I just leave out on the counter tonight or try to put in fridge again. I have never made in advance before so new territory for me. Thank you so much for response and am sorry I didn’t see your response earlier so hopefully can get answer to ight
I would put it in the refrigerator until the morning, then bring it back to room temp (68ºF). I’m not sure why yours ended up thin but if you need to thicken it up, you can either add some cornstarch (up to 1/4 Cup) or more powdered sugar, balanced with salt so that it doesn’t end up too sweet.
Awesome recipe! Made this for a wedding cake in Hawaii. Turned out amazing and held up perfectly in the heat and humidity.
Yay, Ashleigh! That makes me so happy!
Hi, I’m decorating a cake later today and the temp here in the uk has risen to 35 degrees. I’m using crisp n dry shortening as recommended by someone on here. I can’t find meringue powder, only powdered egg white. I guess that’s the same. If adding the egg powder will the buttercream dry out and go hard?
Hi Penny, I’ve never tried adding egg white powder as a sub for meringue powder. I think they’re really similar products, as meringue powder has egg whites listed as an ingredient. I think it’s worth a try!
Hi Penny,
I’m in the same situation as you were. I’m making a smash cake for my baby’s first birthday party here in hot Sydney summer. My first frosting melted and the cake layers slid over each other. I can only find egg white powder. Just wondering how your frosting went with egg white powder rather than meringue powder? Thanks.
I tried to make this and ended up with only 2 cups of sugar. I have to make a cake and cupcakes for wedding outdoor, probably around 82 F. Will less sugar effect the ability to hold the heat?
Hi Fai! Less powdered sugar will affect the consistency of the buttercream by making it thinner, which will ultimately make it less resistant against the heat. I recommend adding the full amount of powdered sugar for best results.
Hi Whitney! It turned out so well, no melt at all. And it wasn’t too sweet even I put the full amount of sugar. Thank you so much again and this will be my favorite summer buttercream.
Yesss! I’m so happy to hear that, Fai!
Hi, I’ve read somewhere that adding a little citric acid to buttercream helps counteract the sweetness. If added to this recipe, do you think it will affect it negatively?
Hi Neka! I’ve never tried that before so it would be an experiment. I don’t find that this buttercream is overly sweet, but feel free to give the citric acid a go if you feel that it needs it! I normally use a little salt to counteract the sweetness.
Can you freeze any leftover buttercream? Trying the recipe in this UK heatwave!
Yes you can! Just be sure to store the buttercream in an airtight container in the freezer, then move it to the refrigerator the day before you want to use it so it can thaw. Bring it to room temperature from there and re-mix with your stand mixer on low to bring it back to frosting consistency before using on future bakes 🙂
Can I replace meringue powder with a cornstarch
Hi Nozy! I have never tried replacing the meringue powder with cornstarch before. My hunch is that it won’t work quite the same, but since I haven’t tested it I don’t know for sure.
Does the meringue powder change the taste or make the frosting taste different?
Not at all!