Preheat oven to 350°F (175°C). Blend Oreo cookies and melted butter until fine crumbs form. Press into the bottom of a 9-inch springform pan.

In a bowl, beat cream cheese and granulated sugar with an electric mixer until smooth. Gradually add eggs, then mix in red velvet cake mix and vanilla extract.

Prepare the vanilla cheesecake by mixing cream cheese, sugar, and vanilla extract until smooth.

Pour the red velvet layer over the crust, then add the vanilla layer on top. Bake for 45-50 minutes until edges are set.

After baking, turn off the oven and let cheesecake cool inside for 1 hour. Cool to room temperature, then refrigerate for at least 6 hours.

For ganache, heat heavy cream until simmering, then pour over chopped dark chocolate. Stir until smooth and glossy, cool slightly before pouring over cheesecake.

Decorate with whipped cream or crushed Oreo crumbs, slice, and serve.