Preheat your oven to 350°F (175°C) and prepare a 9-inch springform pan and an 8-inch round cake pan with parchment paper.

In a medium bowl, whisk together flour, cocoa powder, and salt until blended, then set aside.

In a large mixing bowl, cream together butter and sugar until light and fluffy. Mix in sour cream, vegetable oil, vanilla, eggs, and red food coloring until fully incorporated.

Gradually add the dry ingredients to the wet mixture, alternating with buttermilk. Fold in baking soda and vinegar.

Divide the batter between the prepared pans and bake for 18-20 minutes, or until a toothpick comes out clean. Cool completely in pans.

Crush 20 Oreos and beat cream cheese until smooth. Gradually mix in crushed Oreos, sugar, cornstarch, sour cream, and eggs until creamy.

Fold in 5 crushed Oreos into the cheesecake filling, then pour over cooled cake layers in the springform pan.

Prepare a water bath and bake the cheesecake at 300°F (150°C) for about 90 minutes, then cool gradually in the oven.

For ganache, heat heavy cream, pour over dark chocolate chips, stir until smooth, then cool slightly before pouring over the cheesecake.

Decorate with crumbled red velvet cake and cream cheese frosting, serve with fresh berries or chocolate sauce.