Bake cupcakes according to box directions. Mine called for the water butter and eggs listed in the ingredients. Cupcakes are done when a toothpick inserted into a center cupcake comes out clean.
Immediately turn cupcakes onto a clean surface and allow to cool completely before assembling.
While cupcakes are cooling beat cream cheese in a stand mixer until creamy. Slowly add butter cubes, beating until well combined. Add powdered sugar 1/2 cup at a time, mixing well. Stir in vanilla and scoop into a pastry or gallon zip bag fitted with a Wilton 1M piping tip (if you don't have this tip you can also just cut a small corner off the end of your zip bag instead).
Remove the wrappers from the cupcakes and cut the top off the cupcakes using a serrated knife (save this for cake pops or snacking!) then cut each cupcake in half. Add frosting, a 2nd layer of cake, and repeat until the mini cake has 3 tiers and frosting on top.
Garnish with cake crumbs or red sprinkles.