Double Layer: Cheesecake and Peanut Butter Mousse with Chocolate Ganache on Oreo Cookie Crust

Ingredients for Oreo Crust:
32 Oreo cookies, finely processed into crumbs
5 1/3 tablespoons unsalted butter, melted
Small pinch of salt

Ingredients for Ganache:
1 1/2 cups heavy cream
20 oz. dark chocolate, finely chopped

Ingredients for Cheesecake (from http://www.grouprecipes.com/20528/cooks-illustrated-cheesecake.html, but only the ingredient for the filling was used since I made an Oreo