One Summer, something happened to me that had never happened before (and thankfully hasn’t happened since): 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 85ºF (29ºC). 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.
In light of the melted cake, I decided to conduct some experiments to find the perfect buttercream recipe for hot weather that actually tastes good! The winning recipe can be adapted to make all kinds of flavors and has gone on to help many readers create buttercream cakes that handle the heat of outdoor events all over the world.
One Reader, Shauna, says: “This is my new go to vanilla icing! I used it for my sister’s wedding cake – an outdoor reception in July in the South. It was hot and humid and this cake remained beautiful. Not only did it hold up well, it was absolutely delicious and not nearly as sweet as normal American buttercream. A lifesaver!”
How Hot is Too Hot for a Buttercream Cake?
Whether you’re using American buttercream, Swiss Meringue buttercream, or another butter-based frosting, here’s what happens to buttercream cakes at different temperatures:
- Above 75ºF: the buttercream begins to soften.
- Above 82ºF: the buttercream starts to break down and buttercream details begin to droop.
- Above 90ºF: the buttercream starts to melt completely as it approaches the actual melting point of butter.
Keep in mind that the melting temperature for vegan butter is even lower, so these temperatures shift lower for a vegan buttercream frosted cake (like the melted one pictured above).
Ingredients that Stabilize Buttercream for Hot Weather
There are a few key ingredients that make the winning buttercream more heat stable:
- Shortening. Replacing at least half of the butter in any American buttercream recipe with shortening will make it incredibly heat resistant. If you have access to it, opt for high-ratio shortening for the smoothest flavor and most heat resistance. If you can’t easily find it, Crisco will get the job done.
- Powdered Sugar. In an American buttercream (which is the base of the recipe pictured throughout this post), powdered sugar helps thicken the frosting and create an outer crust for the buttercream that helps keep its shape. I don’t use as much powdered sugar as the average American buttercream recipe which keeps the sweetness level minimal.
- Meringue Powder. This is essentially a mixture of powdered egg whites and other stabilizing ingredients like cream of tartar and gum arabic. Adding a little meringue powder helps absorb moisture and create more structure that helps frosting hold its shape (especially piped details) in warm weather.
Hot Weather Buttercream Recipe Tests
To come up with the winning hot weather buttercream recipe, I conducted an experiment to test out different ingredients for stabilizing. I created four cakes and decorated each with a different frosting using my favorite vanilla buttercream recipe as a base. I tested:
- All butter (aka the recipe as-is)
- Half butter and half shortening
- All shortening in place of the butter in the recipe
- Half vegan butter and half shortening (with coconut milk as the liquid)
After refrigerating each cake until the frosting was firm, I placed them in the direct sun on an 88ºF day. Here’s a video of what happened:
I had the cakes in the sun for 2 hours, but none of them completely melted, which was kind of disappointing because I wanted things to be more dramatic. So in the end, I broke out the hair dryer to see what would happen with more heat applied. After I cranked up the heat on these cakes to the melting point of butter:
- The all-butter buttercream cake: melted into soup. No surprises there.
- The half butter and half shortening cake: started to settle a bit (but nothing crazy). This one had the best flavor for a heat stable buttercream.
- The all-shortening cake: had relatively no change, but the flavor wasn’t as good as it was with half butter.
- The half vegan butter and half shortening cake: got a huge air bubble in the frosting and started to melt.
With taste and stability in mind, if you’re up against heat above 82ºF, I’d recommend using at least half butter and half shortening. If you need even more structure, consider adding some meringue powder (instructions in the recipe below) or using all shortening.
Hot Weather Buttercream FAQ
- Why does high-ratio shortening work better than Crisco? High-ratio shortening (also known as icing shortening) has a high ratio of fat with added emulsifiers and zero water content. This helps the frosting hold more sugar and liquid, makes it more temperature resistant, and the resulting buttercream has a much smoother (not greasy or gritty!) texture.
- What if I can’t find high-ratio shortening anywhere? It’s usually available on Amazon, but if you’re in a pinch, a regular vegetable shortening like Crisco will work just fine.
- Should I add meringue powder? If you’ve got a cake with intricate piping and are concerned about hot weather, I would add about 1 tablespoon of meringue powder per batch of buttercream for extra stability.
- Are there other ways to make heat stable buttercream? Adding shortening to an American buttercream recipe is the easiest way to make a heat stable buttercream, but I’ve also heard that Italian meringue and ermine frosting are both very heat stable.
Best Practices for Cakes at Outdoor Events
Now that you know more about how to make your buttercream cake more heat stable, here are some best practices for ensuring that frosting stays put at an outdoor event:
- Refrigerate the cake until the moment you need to transport it to your event.
- If possible, refrigerate the cake until you’re ready to display it at the event. This way, it should take at least an hour for the cake to come to room temperature while on display (the ideal temperature for eating the cake)!
- Place the cake in the shade, not in the direct sun.
- Read up on the weather and outdoor temperature beforehand, so you know how much extra stability you need in your frosting.
I hope this covers everything you need to know about making buttercream cakes heat stable! If you make this buttercream, let me know how it went in the comments below (don’t forget to rate the recipe!) and feel free to tag @sugarandsparrowco on Instagram if you post a photo. Happy hot weather caking!
Heat Stable Vanilla Buttercream
Ingredients
- 1/2 Cup (113g) unsalted butter, room temperature
- 1/2 Cup (100g) shortening use high-ratio shortening if possible
- 3 1/2 Cups (420g) powdered sugar
- 1 Tbsp meringue powder (optional)*
- 2 tsp vanilla extract
- 2 Tbsp (30ml) 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 (if using) into the powdered sugar. Then, add the meringue/powdered sugar mixture one cup at a time, mixing on low speed and scraping down the bowl and paddle after each addition.
- Add the vanilla, milk, and salt and mix on low speed for another 1-2 minutes, 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!