Grease and flour two cake pans. Combine butter and sugar. Add eggs and beat. Add vanilla. Mix cocoa powder and red food coloring. Blend into the butter.
Combine dry ingredients in a bowl. Add half to butter mixture, and half of the buttermilk. Mix vinegar and repeat. Divide cake batter to two pans. Bake for 18-22 minutes.
Grease and line a springform pan. Beat cream cheese, sugar and cornstarch. More cream cheese. Beat until smooth. Add sugar and vanilla. Add eggs. Don't overmix.
Pour batter in pan. Place in a shallow pan with hot water. Bake until golden brown. Remove cheesecake from water bath to a wire rack. Refrigerate.
Frost the bottom tier of red velvet. Layer cheesecake on top. Frost then add the top red velvet cake. Frost the cake. Make chocolate ganache and pour on the sides.