Chocolate and Vanilla Red Velvet Cake

1. Allow eggs and butter to stand at room temperature for 30 minutes. Meanwhile, grease and lightly flour three 9x9x2-inch square cake pans.** Set pans aside. In a medium bowl, stir together flour, cocoa powder, and salt; set aside.

2. Preheat oven to 350°F. In a very large bowl, beat butter with an electric mixer on medium to high speed for 30 seconds. Gradually add sugar, about 1/4 cup at time, beating on medium speed until well mixed. Scrape side of bowl; beat on medium speed for 2 minutes more. Add eggs one at a time, beating well after each addition. Beat in red food coloring and vanilla. Alternately add flour mixture and buttermilk, beating on low speed after each addition just until combined. In a small bowl, combine baking soda and vinegar; fold into batter. Spread batter in the prepared pans.

3. Bake for 20 to 25 minutes or until a wooden toothpick inserted near the centers comes out clean. Cool cake layers in pans on wire racks for 10 minutes. Remove cake layers from pans. Cool thoroughly on wire racks.

4. If necessary, with a long serrated knife, level tops of cake layers. Place one cake layer, bottom side up, on serving platter. Spread with half of the Mascarpone-Vanilla Bean Filling. Top with second cake layer, bottom side up. Spread top with the remaining filling. Top with third layer, bottom side up. Spoon Chocolate Ganache over cake top, using a thin spatula to spread on side and top.

Mascarpone-Vanilla Bean Filling

1. In a small saucepan, combine chocolate and whipping cream. Cut a vanilla bean in half lengthwise; scrape out seeds. Stir vanilla bean seeds into chocolate mixture. Cook and stir over low heat until chocolate is nearly melted. Remove from heat; stir until smooth. Cool for 15 minutes. In a large bowl, beat together mascarpone cheese and butter with an electric mixer on medium speed. Gradually add white chocolate mixture, beating until fluffy. Gradually beat in powdered sugar until mixture is a thick spreading consistency.

Chocolate Ganache

1. In a medium saucepan, bring cream and corn syrup just to boiling over medium-high heat. Remove from heat. Add chocolate pieces (do not stir). Let stand for 5 minutes. Stir until smooth. Let stand for 15 minutes more.

*Test kitchen tip

To make 1-1/2 cups sour milk, place 4-1/2 teaspoons lemon juice or vinegar in a glass measuring cup. Add enough milk to make 1-1/2 cups total liquid; stir. Let the mixture stand for 5 minutes before using.

**Test kitchen tip

If you have only one square pan, bake one layer at a time. Cool cake as directed in pan, then turn onto a wire rack. Wash and dry the pan. Grease and flour. Repeat baking each layer. Store cake batter in the refrigerator until ready to bake.

To make ahead:

Prepare as directed through Step 3. Place cakes in an airtight container; cover. Store at room temperature for up to 3 days or freeze for up to 1 month. Thaw cakes, if frozen. Continue as directed in Step 4.