Heat Classic Milk Fondue according to package directions.
Spray a 20 cm (8") diameter springform pan with cooking spray, then line the bottom of the pan with parchment paper. Place a rhodoid ribbon around the side of the pan.
Mix crust ingredients in a bowl. Pour the mixture into the mould and press firmly to even out the surface. Place in the freezer for 15 minutes.
In another bowl, whisk cream cheese with sugar and cocoa until smooth. Pour the fondue into the bowl and whisk until smooth.
Gradually fold in the whipped topping with a spatula until smooth.
Add the chopped sandwich cookies to the mixture and stir gently with the spatula.
Transfer the mixture to the mold and smooth the surface. Refrigerate for 3 to 4 hours.
Carefully unmold the cake onto a serving platter.
Fill a pastry bag fitted with a fluted tip with whipped topping. Pipe rosettes of whipped topping onto the cake, then decorate with sandwich cookies.