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Rainbow cake slice with swiss buttercream
5 from 2 votes

Italian Meringue Buttercream

Ingredients

  • 12 oz granulated sugar
  • 3 oz water
  • 3/4 cup egg whites
  • 18 oz unsalted butter, cut into 1-inch cubes, room temp

Instructions

  • In a saucepan, combine sugar and water. Stir until it resembles wet sand.  Set to high heat and cook and cook until candy thermometer reads 245 degrees F. While the heat is on, DO NOT stir or disturb the sugar solution. Agitation will cause unwanted cystallization. If any sugar splashes onto the sides of the saucepan, use a clean pastry brush soaked in water to dilute any crystal formation.
  • While the sugar is cooking, whip the egg whites in the bowl of a stand mixer with a whisk attachment. Keep it at low speed until whites are foamy (it should look like the foam on top of beer).  Once foamy, begin whipping at medium speed.  Before you add the sugar, lower the speed slightly.
  • Once sugar reaches 245 degrees F, pour it into the whipping egg whites in a slow and steady stream. After all the sugar has been added, increased the speed to high. Continue to whip until the mixing bowl is slightly warm than room temperature to the touch.
  • Turn down the mixer to medium speed and slowly add the butter, a couple cubes at a time. Continue to whip at medium speed until all the butter has been added. Whip until buttercream is smooth and creamy.

Notes

  • If you add the butter when the meringue is too hot, it may melt and the buttercream may not emulsify.  If this happens, place the mixing bowl in the freezer for a couple minutes to cool down the mixture.  Once cooled, started whipping again.
  • If the butter is too cold when added to the meringue, the buttercream may end up chunky.  Use a torch to warm the bowl or place over a bain-maire to soften the butter.