Preheat the oven to 180C/350 and grease 3 8-inch cake pans with cooking spray and set aside.
Prepare the brownies as directed. Distribute the batter amongst the 3 cake pans. Bake for 25-30 minutes, or until a skewer comes out clean. Let cool completely.
Prepare your edible cookie dough as directed. If desired, add peanut butter into it. Using a tablespoon, slowly add milk of choice until a smooth batter remains.
Once your brownies have cooled, prepare the first brownie layer. Lay a thin layer of chocolate frosting, followed by half the cookie dough. Repeat again and top with the final brownie layer. Top with extra chocolate frosting. Refrigerate for an hour, to firm up.
* If you'd like this recipe to be low carb, make keto brownies.** You can also use keto cookie dough.*** You may need much more milk than suggested. You want your cookie dough to be thick and spreadable. TO STORE: Leftover slices of the cake should be stored in the refrigerator, in a sealed container, for up to 2 weeks. TO FREEZE: Place leftover cake in a freezer friendly container and store in the freezer for up to 6 months. Thaw overnight in the refrigerator.