Champagne Cupcakes

Ingredients (15)

• 2 3/4 cups all-purpose flour
• 1 tablespoon baking powder
• 1 teaspoon salt
• 6 egg whites, at room temperature
• 2/3 cup butter, softened
• 1 1/2 cups granulated sugar
• 2 egg yolks, at room temperature
• 1 teaspoon vanilla extract
• 3/4 cup Champagne
• 6 tablespoons butter, softened
• 4 cups confectioners' sugar
• 1 teaspoon vanilla
• 4 tablespoons Champagne
• White sanding sugar, for garnish
• Silver or gold decorations, for garnish