In an electric mixer, beat 2 cups of cream cheese with 1 ½ cups of granulated sugar for about a minute at medium speed. Once the sugar and cheese mixture has softened and combined thoroughly, add the lightly beaten eggs along with cocoa, buttermilk, sour cream, vanilla extract, red food coloring, and white vinegar. When all the ingredients are fully incorporated in the mixture and you have a thick batter, pour this cake batter over the graham cracker layer.