Red Velvet Cheesecake with Buttercream Frosting

Step 1
Preheat oven to 350 degrees F (175 degrees C). Place a pan of hot water in the bottom of the oven.

Step 2
Line two 9-inch springform pans with aluminum foil; grease with cooking spray.

Step 3
Beat cream cheese in a bowl with an electric mixer until smooth, about 3 minutes. Add 1 1/2 cup white sugar and cornstarch; beat until smooth. Add 1 tablespoon vanilla extract. Beat in 2 eggs and 2 egg whites, 2 at a time, until batter is creamy. Add heavy cream; beat just until batter is free of lumps and fluffy.

Step 4
Divide batter between the prepared pans.

Step 5
Bake in the preheated oven until edges appear set, about 40 minutes. Turn off oven; leave cheesecakes inside for 1 to 2 hours. Chill until firm, at least 4 hours or overnight.

Step 6
Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 9-inch round cake pan.

Step 7
Whisk buttermilk and 3/4 teaspoon vanilla extract together in a small bowl.

Step 8
Whisk flour, cocoa powder, cinnamon, baking soda, and salt together in a separate bowl.

Step 9
Beat 1 1/4 cup white sugar and oil with an electric mixer until creamy. Whisk in 2 eggs, one at a time. Add vinegar and red food coloring; beat well. Beat in flour mixture in 3 additions, alternating with buttermilk mixture, until batter is smooth. Pour batter into the prepared pan.

Step 10
Bake in the preheated oven until a toothpick inserted into the center comes out clean, about 50 minutes. Cool for 10 to 15 minutes in the pan. Invert onto a wire rack. Cut horizontally into 2 even layers. Chill until firm, at least 4 hours to overnight.

Step 11
Combine butter, shortening, and marshmallow cream in a large bowl; beat with an electric mixer on high speed until creamy. Add 1 1/2 teaspoon vanilla extract; beat until light and fluffy. Add confectioners' sugar 1 cup at a time, beating until frosting is smooth.

Step 12
Place 1 cake layer on a serving plate. Spread a thin layer of frosting on top; stack 1 cheesecake layer over cake. Spread a thin layer of frosting over cheesecake; repeat layers. Spread frosting over top and sides of cake.