Bake the red velvet layers

• Preheat the oven and grease the springform pans.
• Whisk the cake mix with the eggs, oil and water until smooth.
• Divide the batter between the pans and bake until a skewer comes out clean.

Make the Oreo crust

• Crush the Oreo cookies into fine crumbs.
• Mix the crumbs with the melted butter until sandy.
• Press the mixture firmly into the base of a springform pan and chill.

Prepare the cheesecake filling

• Beat the cream cheese and granulated sugar until smooth.
• Mix in the sour cream, eggs and vanilla extract.
• Fold in the remaining crushed Oreo cookies.

Bake the cheesecake

• Pour the filling over the chilled crust and smooth the top.
• Bake until the center is just set with a slight wobble.
• Cool completely, then chill in the fridge.

Whip the cream frosting

• Whip the cold heavy cream with the powdered sugar to stiff peaks.

Assemble the cake

• Place a red velvet layer on a serving plate and spread frosting on top.
• Set the cheesecake layer over it and add more frosting.
• Top with the second red velvet layer and cover the whole cake with the remaining frosting.
• Decorate with crushed Oreo cookies and chill before slicing.