How To Make Swiss Meringue Buttercream Gather your room temperature unsalted butter, sugar, eggs, and vanilla Separate your eggs white from the yolks Add your sugar to your egg whites Give them a whisk to combine Create a double boiler on your stove top. Cook mixture until 160F Transfer back to standing mixer with whisk attachment. Whisk for 8-12 minutes until you achieve stiff picks and bowl is room temperature Use paddle. Add in butter 2 tbsp at a time ensuring completely mixed before next addition Add in vanilla and mix at high speed for 1 minute 2 cups unsalted butter, 5 egg whites, 1 1/2 cups granulated sugar, 2 tsp vanilla