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Keto Swiss Meringue Buttercream

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This is our guide to making the softest, silky smooth keto buttercream that holds its shape beautifully and is perfect for piping on top of keto cupcakes!

Making Keto Swiss Meringue Buttercream can seem a little intimidating, and admittedly it is more complicated than Classic Keto Buttercream Frosting. But don't worry, we've got you covered. This recipe is where you start if you've never tried Swiss meringue buttercream before!

Just like the classic Swiss meringue buttercream, this keto-friendly recipe uses cooked egg whites which are beaten with sweetener until fluffy, stiff peaks form. Once the mixture has cooled down, unsalted butter is slowly beaten into the mixture. Finally, any flavours such as vanilla, cinnamon, or chocolate are added to make vanilla, chocolate, cinnamon, caramel or berry frosting flavours.

This keto Swiss Meringue frosting is not extra sweet like traditional American buttercream frosting. You will still need to use a lot of sweetener but it's more pleasant and still perfectly pipe-able.

How To Make Low-Carb Swiss Meringue Buttercream

Apart from the recipe steps below, here are my top tips for the best silky smooth Keto Swiss Meringue Buttercream Frosting.

  • Fresh egg whites are best. Use fresh egg whites over cartoned egg whites for best results.
  • Use slightly cooler than room temperature butter. Too warm and it will be thin, too cold and it may split. If any of this happens to you, don’t panic, read my top tips on how to fix it them below in the troubleshooting sections. Basically, the butter should be just cool to touch and easy to cut into cubes.
  • Adjust sweetness to your taste. You can use 2 cups or up to 2 1/2 cups of granulated Allulose or other low-carb sweetener such as Erythritol or Swerve. Allulose works best as it tastes just like sugar with no aftertaste, and it will keep the buttercream smooth and silky without any gritty bits. Do not use less than 2 cups of sweetener as that may affect the texture.
  • Flavor variations. If you are planning to make other flavours by using ingredients like cocoa powder, caramel sauce or freeze-dried berry powder, add these ingredients after the butter is well incorporated.
  • How many servings does this recipe make? This makes about 3 cups and is enough to pipe a tall cupcake. If just spreading you can half this mix.
  • Storing buttercream. This sugar-free Swiss Meringue Buttercream can be left uncovered at room temperature for 2 days. After that refrigerate for up to 4 days or freeze for 3 months. If freezing, allow to come to room temp and beat with a paddle attachment for a couple of minutes until smooth again.
  • Freeze for longer storage. For longer storage, you can freeze the buttercream for up to 3 months. When ready to use, thaw it at room temperature on the counter. Once the frosting reaches room temperature, place into the bowl of your stand mixer. Beat with a paddle attachment for 2 to 3 minutes until soft and creamy again. If it separates or curdles, see troubleshooting tips below.

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Troubleshooting Keto Swiss Meringue Buttercream Frosting

1. The Eggs Whites Won’t Stiffen

  • Ensure your equipment is clean and dry. Wipe with lemon juice or white wine vinegar first.
  • If any egg yolk gets into the egg whites, it will not whip into stiff peaks so ensure the whites are cleanly separated.

2. My Buttercream Has Curdled

  • Don’t panic, there’s an easy fix for this, and it happens to be most of the time so very common. Firstly, keep mixing as the butter may fix itself.
  • If this doesn’t work and your mix is just getting thicker, place your mix in a heatproof bowl over a pan of simmering water (like you would with chocolate in a bain marie) let the edges warm a little, don’t stir. Don’t let the bowl touch the bottom of the water. It should stay above it.
  • You can also do this with the stainless steel bowl of the kitchen aid just hold it above the pan (careful not to burn your fingers). The centre of your mix should remain solid, so just about 1 minute to lose the sides then remove from the heat and pop back in the mixer. Start on low for about 1 minute and then back to medium-high until smooth. Keep mixing. It will right itself.

3. My Buttercream is Too Thin

  • This probably means your butter was too warm. To fix this just pop your mix in the fridge for about 15 minutes to cool down then place back in the mixer and beat on medium-high till thick.
  • If it then curdles, follow the tip on curdling!

4. My Buttercream Went Hard in the Fridge

  • Buttercream is made from butter so it will go hard in the fridge. Either let it come to room temp naturally or pop it back in your mixer and beat for 2 minutes until it warms up and is creamy again.
  • If it’s still not warm enough then follow the tip in my buttercream has curdled and you should be fine.

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Hands-on Overall

Serving size about 1/3 cup/ 80 g/ 2.8 oz

Allergy information for Keto Swiss Meringue Buttercream

✔  Gluten free
✔  Nut free
✔  Nightshade free
✔  Pork free
✔  Avocado free
✔  Coconut free
✔  Fish free
✔  Shellfish free
✔  Beef free

Nutritional values (per serving, about 1/3 cup/ 80 g/ 2.8 oz)

Net carbs1.8 grams
Protein2 grams
Fat22.9 grams
Calories219 kcal
Calories from carbs 3%, protein 4%, fat 93%
Total carbs1.8 gramsFiber0 gramsSugars1.8 gramsSaturated fat14.3 gramsSodium43 mg(2% RDA)Magnesium2 mg(1% RDA)Potassium34 mg(2% EMR)

Ingredients (makes about 4 cups)

  • 6 large egg whites
  • 2 cups granulated Allulose or Erythritol or Swerve (400 g/ 14.1 oz)
  • 3 sticks unsalted butter, cut into cubes (340 g/ 12 oz)
  • 2 tsp sugar-free vanilla extract
  • pinch of sea salt


  1. Ensure all your equipment is clean and dry. Wipe with lemon juice or vinegar if you like. Separate the eggs, ensuring no yolks enter the whites (or this can result in floppy egg whites!)
  2. Whisk the granulated Allulose (or Erythritol or Swerve) into the egg whites with a hand balloon whisk then add to a heatproof bowl over a pan of simmering water. Ensure the bowl is above the water line. Keto Swiss Meringue Buttercream
  3. Whisk the whites and sweetener continuously with a hand ballon whisk until the allulose dissolves, about 4 minutes. If using a thermometer, if should reach about 70 °C/ 160 °F.
  4. Immediately transfer to a stand mixer. You can use a hand mixer instead but be warned it takes a while so your arms may ache!
  5. Beat for about 15 - 17 minutes on medium - high using the whisk attachment until glossy. If it’s a warm day it may take a little longer, up to 20 mins. If the bowl and meringue still feel warm, wait until both cool to room temperature (around 21 °C/ 70 °F) before adding the butter in the next step.
    Note: Feel free to place it in the refrigerator. A warm bowl and meringue will melt the butter. I put mine in the fridge for 15 minutes.
    Keto Swiss Meringue Buttercream
  6. Replace the whisk attachment with a paddle. Add the cubed butter, 1 tablespoon at a time and beat, waiting for each to be incorporated before adding the next. Once all the butter has been added, turn the speed down to medium and add the vanilla and salt until combined.
    Note: If your mix is too thin or it curdles, see the troubleshooting section in the post above on how to easily fix it.
    Keto Swiss Meringue Buttercream
  7. Use as frosting for cupcakes or store in the fridge until ready to use. You can store this keto Swiss meringue buttercream at room temperature for up to 2 days, refrigerate for up to 5 days. Keto Swiss Meringue Buttercream
  8. Optionally, sprinkle with cocoa powder, cinnamon or freeze-dried berries. Keto Swiss Meringue Buttercream

Ingredient nutritional breakdown (per serving, about 1/3 cup/ 80 g/ 2.8 oz)

Net carbsProteinFatCalories
Egg white, fresh
0.1 g1.8 g0 g9 kcal
Erythritol (natural low-carb sweetener)
1.7 g0 g0 g7 kcal
Butter, unsalted, grass-fed
0 g0.2 g22.9 g203 kcal
Vanilla extract, sugar-free, alcohol-based
0 g0 g0 g2 kcal
Salt, sea salt
0 g0 g0 g0 kcal
Total per serving, about 1/3 cup/ 80 g/ 2.8 oz
1.8 g2 g22.9 g219 kcal

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Jo Harding
Creator of

Jo Harding

Food is one of life’s most powerful medicines. I’m a true testament that once you find the right approach for you, you can overcome poor health through the healing power of food.

I believe the secret to radiant health starts and ends with a healthy gut so my recipes are all grain, gluten and refined sugar free. Most are also dairy-free.

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