Project Birthday Cake Part #2: Swiss Buttercream

Well, you can't have a cake without frosting, right? I decided to go with one of Smitten Kitchen's suggestions -- the Swiss Buttercream she raves about. (I used the version for the 9" round.)

Swiss Buttercream
From: Smitten Kitchen

1 cup sugar
4 large egg whites
26 tablespoons butter, softened (3 sticks plus 2 tablespoons)
1 teaspoon vanilla extract

Whisk egg whites and sugar together in a big metal bowl over a pot of simmering water. Whisk occasionally until you can’t feel the sugar granules when you rub the mixture between your fingers.

Transfer mixture into the mixer and whip until it turns white and about doubles in size. (Make sure you wipe the condensation off the bottom of the bowl so that no water gets into the egg whites when moving the bowl. This can keep them from whipping up properly.)

Add the vanilla.

Finally, add the butter a stick at a time and whip, whip, whip.