Supplies you'll need:
Skewers or toothpicks
Plain round cutters, various sizes
Chocolate sheet cake or brownie sheet, 1" deep
Whether it's made from scratch or your friend Betty Crocker, bake your cake flat in a shallow sheet pan so it only rises up to an inch. Once cool, trim the top with a serrated knife using a sawing motion to form an even, flat surface. This will be flipped over, so don't worry about imperfections!
Both brownies and cake work well, but with the latter you will have to be more careful to achieve clean edges. Carefully twist the round cutters into the sheet cake with desired sizes for each tier. For this example, we used 1.25", 2.5", and 3.5" cutters.
Assemble the tiers on top of each other, with the flattest surface facing up (usually the bottom-side of the cake). Insert toothpick to secure tiers together. If using skewers, measure against the assembled mini cake, and trim a few millimeters short of the full height so it doesn't protrude.
Lightly dust cakes with powdered sugar. Wrap, and enjoy!