1. Preheat the oven to 325°F and prepare a springform pan by greasing it and lining the bottom with parchment paper.
2. Make the Oreo crust by crushing Oreos into fine crumbs, mixing with melted butter and sugar, then pressing the mixture into the bottom of the pan.
3. Bake the crust for about 10 minutes, then let it cool while preparing the cheesecake layer.
4. In a mixing bowl, beat cream cheese until smooth, then add sugar and mix until well combined.
5. Add eggs one at a time, mixing on low speed, followed by sour cream, cocoa powder, and vanilla extract.
6. Pour the cheesecake batter over the cooled Oreo crust and smooth the top.
7. Prepare a water bath by wrapping the outside of the springform pan in aluminum foil and placing it in a larger baking dish filled with hot water.
8. Bake the cheesecake for about 45-60 minutes until the center is slightly jiggly.
9. Turn off the oven and let the cheesecake sit inside for an hour to cool gradually.
10. Remove from the oven, let it cool to room temperature, then refrigerate for at least 6 hours or overnight.
11. Prepare the red velvet cake batter by whisking together flour, cocoa powder, and salt in a bowl.
12. In another bowl, beat butter and sugar until fluffy, then add eggs one at a time.
13. Mix in buttermilk, red food coloring, vinegar, and vanilla extract.
14. Gradually add the dry ingredients to the wet mixture, mixing until just combined.
15. Divide the batter equally between two greased cake pans and bake for about 25-30 minutes.
16. Let the cakes cool completely, then level the tops if necessary.
17. Make the cream cheese frosting by beating cream cheese and butter until smooth, then mixing in powdered sugar and vanilla extract.
18. Assemble the cheesecake by placing one red velvet cake layer on a serving plate, adding the cheesecake layer, and topping with the second red velvet layer.
19. Frost the entire cake with the cream cheese frosting, smoothing the sides and top.
20. Chill the cake for another hour before slicing and serving.