Step 1

OREO CRUST: Lightly grease a 9-inch springform or pie pan with cooking spray. Melt 4 tbsp. butter in a microwave-safe bowl. Once melted, set aside to cool for 5 minutes. (Hot butter will cause a greasy crust.) In a blender or food processor, process the whole cookies (don't separate cookie from cream) until they are all fine crumbs (re-blend any large chunks). Measure to get a level 1 and 3/4 cups of crumbs and add to a large bowl. Add salt to the bowl. Use a spatula to scrape in every bit of butter and mix until well combined.

Step 2

FINISH CRUST: Empty the crumb mixture into the prepared pan. Using your fingers, press the crumbs into just the bottom of the pan (if using a springform pan) and up the sides (if using a pie pan). Use the bottom of a flat 1-cup measuring cup to thoroughly compress the crumbs into a firm crust. Place in the freezer while preparing the filling.

Step 3

FILLING: Add the softened (to room temperature) cream cheese to a large bowl and beat for about 45 seconds or until creamy. Add in the sweetened condensed milk and beat until the mixture is completely combined and smooth. Scrape the sides of your bowl with a spatula. Add in the hot cocoa mixes and again beat to combine. Beat in the cocoa powder until integrated.

Step 4

FILLING CONTINUED: Add in the completely thawed whipped topping and using a spatula, gently fold into the mixture until completely integrated (no dark streaks of the chocolate mixture remains -- the filling should be an even light brown color). Be careful to not over mix the whipped topping, but ensure it's well combined with the other filling ingredients. Finally, add in the dehydrated marshmallows (if using) and gently fold through.

Step 5

FREEZE: Pour the mixture into the pan on top of the Oreo crust. Smooth the top with a spatula. Cover pan and freeze overnight or for at least 8 hours. When ready to serve, remove cheesecake from the freezer and cut into slices with a sharp knife (Note 4). If desired, garnish individual slices with whipped cream.

Step 6

LEFTOVERS: Cover any leftovers tightly and return promptly to the freezer.