CARAMEL BUTTERCREAM FROSTING FOR BROWN-SUGAR LAYER CAKE

Steps:

• Combine 1 1/4 cups sugar and the water in a medium saucepan. Bring to a boil, stirring to dissolve sugar. Brush down sides of pan with a damp pastry brush, and cook, without stirring, until dark amber. Remove from heat, and gradually stir in cream until completely smooth.
• Whisk together remaining sugar and the egg whites in the bowl of a mixer set over a pot of simmering water. Whisk until sugar dissolves and mixture is warm. Transfer bowl to a stand mixer fitted with the whisk attachment, and whisk on medium-high speed until fluffy and cool and stiff peaks form, about 10 minutes. Add butter, 2 tablespoons at a time, whisking well after each addition. Whisk in vanilla. Slowly pour in caramel with mixer on medium speed, and whisk until completely incorporated. Continue to whisk until smooth, about 3 minutes. Use immediately, or transfer to an airtight container and refrigerate up to 3 days. Before using, bring to room temperature, and beat until smooth.