Preheat the oven to 350ºF.

In a food processor or blender, pulse the oreos (the cookie portion and the cream filling) into fine crumbs.

In a mixing bowl, use a spatula to combine the crumbs with the melted butter until well combined.

Transfer the crumbs to a 9 inch pan. Use the bottom of a measuring cup or drinking glass to pack / tamp the crumbs evenly and tightly into and up the sides of the pan.

Bake the pie crust for 8-10 minutes. Cool the crust completely before using.

In a mixing bowl, combine the melted butter, granulated sugar, egg, vegetable oil and vanilla extract. Whisk until combined.

Gradually mix in the flour, cocoa powder and salt. The batter will be thick.

Spread the brownie batter on top of the oreo crust and bake for 25-35 minutes or until the center of the brownie looks set and puffy. Cool completely, about 2-3 hours.

In a stand mixer or mixing bowl, combine the pudding mix and heavy cream with an electric mixer until well blended. You will NOT prepare the pudding mix as directed on the box. When you beat the pudding mix and heavy cream together, the mixture will be VERY thick.

Spread the mousse layer on top of the brownie layer. Refrigerate for 1-2 hours.

Place a metal or glass mixing bowl and beaters in the freezer for 15 minutes.

Remove the bowl from the freezer. Add in the heavy whipping cream, powdered sugar, and vanilla extract, beat with an electric mixer for 4-5 minutes on high speed, or until stiff peaks form / it’s scoop-able with a spoon and holds its shape.

Spread the whipped cream on top of the chocolate pudding mousse layer. Refrigerate until ready to serve.

Optional: Top with leftover oreo crumbs, chocolate shavings or chocolate curls.