How To Make Chocolate Cupcakes With Vanilla Icing. You will need. 1-1/2 cups all-purpose flour, 3/4 teaspoon baking soda, 3/4 baking powder, 1/2 teaspoon salt, 6 tablespoons unsalted butter, 1 cup brown sugar, 2 large egg yolks, 4 ounces unsweetened chocolate melted, 1 large egg white, 1-1/4 cups milk, 2 teaspoons vanilla, 4 ounces unsalted butter softened, 3 cups confectioners sugar. Step 1. Preheat oven to 350 degrees. Line a muffin pan. In a bowl mixes together flour, baking powder, baking soda, and salt set aside. Step 2. In a large bowl, cream butter with brown sugar. Beat yolks and beating until smooth. Stir in chocolate. Beat egg white until smooth then fold into batter. Add half of the dry ingredients to batter, and beat gently while adding 1/2 cup of milk and 1 teaspoon vanilla. Repeat with remaining dry ingredients, then another 1/2 cup milk. Step 3. Pour batter into pan, nearly filling each mold. Bake 18 to 20 minutes, or until a toothpick inserted into center comes out clean. Remove from oven, and let cool in pan for 5 minutes. Remove cupcakes and place on a cooling rack until cupcakes are completely cool. Step 4. In a bowl, beat remaining butter, confectioners sugar, remaining milk and vanilla until creamy. Spread over cooled cupcakes. Enjoy.