Preheat oven to 350ºF and line a large baking sheet (12 in. x 17 in.) with parchment paper. Prepare cake mix according to package instructions. Pour batter into pan and spread evenly with a spatula. Bake 15-17 minutes or until cake springs back when you gently press on it. Allow cake to cool completely.

In a large mixing bowl, use a fork to combine the crushed cookies with the melted butter. Press mixture into the bottom and up the sides of a 9-inch pie pan. Refrigerate crust while you work on the truffle filling.

Place a third of the cooled cake into a large bowl. Add the cream cheese and frosting and use a fork to smush ingredients together until a dough is formed. Press filling into the bottom of the crust.

In the bowl of a stand mixer fitted a paddle attachment, beat the cream cheese and Rainbow Chip frosting together until combined. Fold in the whipped topping. Spread evenly on top of truffle layer.

Spread an even layer of whipped topping/cream on top. Cut a third of the remaining Funfetti cake into cubes, then place around the edge of the pie. Refrigerate pie for at least 4 hours, or overnight.

Just before serving, top with more sprinkles. Serve immediately, or store in the refrigerator for up to 5 days.