Swiss meringue buttercream has a reputation for being challenging to make, but follow this recipe and it won’t be so difficult after all.
This recipe is courtesy of Handle the Heat.
Wipe the bowl of an electric mixer with paper towel and lemon juice or vinegar to remove any grease.
Make a double boiler by placing the mixer’s bowl over a saucepan of simmering water, making sure that the water doesn’t touch the base of the bowl.
Add the egg whites and sugar to the bowl, whisking constantly but gently, until it reaches 140 degrees F, or until the sugar has completely dissolved and the egg whites feel hot.
Attach the bowl to the mixer fitted with the whisk attachment. Whip until the meringue is thick, glossy, and the bottom of the bowl no longer feels warm, about 10 minutes.
Switch the whisk attachment for the paddle attachment. Turn the mixer on to low speed, and add the butter cubes one at a time, until incorporated. Continue beating until it has a silky smooth texture. If it curdles, keep mixing and it will become smooth again. If it’s too thin and runny, refrigerate it for 15 minutes, and then continue beating.
Add the vanilla and salt, and continue beating on low speed until well combined.
Frosting will keep in an airtight container in the refrigerator for up to 1 week, and in the freezer for up to 2 months. Let come to room temperature and re-whip using the paddle attachment before using.