Nutella Swiss Meringue Buttercream
(adapted from How To Eat A Cupcake--food blog)

Makes about 4 cups (enough to generously frost 24 cupcakes or, in my case, 2-9inch rounds)

4 large egg whites
1 1/4 c sugar
1 c unsalted butter, (2 sticks), softened, cut into tablespoons
1/2 jar of Nutella (about 1/2 - 2/3 cup)

Put egg whites and sugar into the top of a double boiler over a pan of simmering water. Whisking constantly, cook until sugar has dissolved and mixture is warm (about 160 degrees). Pour heated egg whites into the bowl of an electric mixer fitted with the whisk attachment. Beat egg white mixture on high speed until it forms stiff (but not dry) peaks. Continue beating until fluffy and cooled, about 7 minutes total. Switch to the paddle attachment. With mixer on medium-low, add butter two tablespoons at a time, beating well after each addition. Increase speed to medium-high; continue beating until frosting appears thick, about 3 minutes. Reduce speed to low; add Nutella a few tablespoons at a time and continue beating until incorporated.