Store-bought peppermint bark makes for easy—and festive—decorating on this Christmas cake. INGREDIENTS Cooking spray 3 1/2 c. cake flour, spooned and leveled 2 1/2 tsp. baking powder 3/4 tsp. baking soda 1/2 tsp. kosher salt 1 c. (2 sticks) unsalted butter, at room temperature 1 1/2 c. granulated sugar 6 large egg whites, at room temperature 2 tsp. pure vanilla …
