Prepare the Red Velvet Cake Base

1. Preheat your oven to 350°F (175°C). Line a 9-inch springform pan and an 8-inch round cake pan with parchment paper and spray with non-stick spray.
2. In a bowl, whisk together the flour, cocoa powder, and salt.
3. Cream the butter and sugar until light and fluffy. Mix in sour cream, oil, vanilla, eggs, and red food coloring until smooth.
4. Gradually alternate adding dry ingredients and buttermilk. Mix in baking soda and vinegar.
5. Divide the batter between pans and bake for 18-20 minutes. Cool completely.

2. Make the Oreo Cheesecake Filling

1. Blend Oreo wafers into fine crumbs and press them into the springform pan base.
2. Beat cream cheese, Oreo filling, sugar, and cornstarch until smooth.
3. Mix in sour cream and vanilla. Add eggs one at a time, followed by chopped Oreos.
4. Pour cheesecake batter over the cooled red velvet cake base in the springform pan.

3. Bake the Cheesecake

1. Wrap the springform pan in foil and place it in a larger pan. Fill the outer pan with hot water.
2. Bake at 300°F (150°C) for 1 hour and 30 minutes. The center should slightly jiggle.
3. Cool in the oven with the door slightly open for 1 hour, then refrigerate overnight.

4. Make the Ganache

1. Melt chocolate chips with heavy cream in the microwave, stirring until smooth.
2. Pour the ganache over the chilled cheesecake and spread evenly.

5. Decorate and Serve

1. Crumble reserved red velvet cake and press along the sides of the cheesecake.
2. Pipe cream cheese frosting on top and garnish with chopped Oreos.
3. Slice into bite-sized pieces and serve chilled.