Preheat oven to 350°F (177°C). Line the bottom and sides of a 9-inch square baking pan with parchment paper, leaving an overhang on the sides to lift the finished bars out (makes cutting easier!). Set aside.

In a food processor or blender, pulse 22 Oreos (including the cream filling) into a fine crumb. You should have about 2 cups (packed) crumbs, or 250g. Pour crumbs into a large bowl. Add the melted butter and stir to combine. The mixture will be thick and quite wet. Try to smash/break up any large chunks. Pour the mixture into prepared pan. With medium pressure using your hand, pat the crumbs down into the bottom to make a compact, thick crust. Bake for 10 minutes, and then cool for 10 minutes before spreading the filling on top. Leave oven on.

Beat cream cheese, egg, sugar, and vanilla extract together with a hand or stand mixer until smooth and creamy, about 3 full minutes. Fold in the Snickers and spread the mixture over your slightly cooled crust. Top with chocolate chips.

Bake for 30–35 minutes, or until the cheesecake has set up and the edges are lightly browned. Allow to cool for 30 minutes on the counter and then completely in the refrigerator for at least 3 hours. Lift the parchment paper out of the pan and cut the cheesecake into squares.

Store bars in a covered container for up to 10 days in the refrigerator.