Step 1: Prepare the Crust

1. Preheat oven to 325°F (163°C). Grease a 9-inch springform pan and line the bottom with parchment paper.
2. In a bowl, combine Oreo crumbs and melted butter, mixing until evenly coated.
3. Press the mixture firmly into the bottom of the prepared pan. Bake for 8 minutes, then let it cool while preparing the cheesecake layer.

Step 2: Make the Cheesecake Layer

1. In a large mixing bowl, beat the cream cheese and sugar until smooth.
2. Add the vanilla extract, then beat in the eggs, one at a time.
3. Mix in the sour cream until smooth. Pour the cheesecake batter over the cooled crust and spread evenly.

Step 3: Prepare the Red Velvet Cake Layer

1. In a medium bowl, whisk together the flour, sugar, cocoa powder, baking soda, and salt.
2. In another bowl, whisk together the vegetable oil, buttermilk, egg, vinegar, vanilla extract, and red food coloring.
3. Gradually add the dry ingredients to the wet ingredients, stirring just until combined.
4. Carefully spoon the red velvet batter over the cheesecake layer and spread it evenly.

Step 4: Bake the Cheesecake

1. Bake at 325°F (163°C) for 50-55 minutes, or until the center is set and a toothpick inserted in the cake comes out clean.
2. Turn off the oven and let the cheesecake cool inside with the door slightly open for 30 minutes.
3. Remove from the oven and cool completely at room temperature before refrigerating for at least 4 hours or overnight.

Step 5: Make the Cream Cheese Frosting (Optional)

1. Beat the cream cheese and butter together until smooth.
2. Add the powdered sugar and vanilla extract, beating until creamy.
3. Spread or pipe the frosting over the cheesecake before serving.