to do this, use a recipe calling for two 9″ cake pans. bake one 9″ cake pan with half the batter, and bake two 6″ cake pans with the other half. two 6″ cake pans is almost the same volume of a 9″ cake pan. the adjustments in baking powder are minimal, so i don’t adjust any baking powder when baking on 9″ to 6″ cake pans.
the top tier is a 3″ cutout from the first tier.
the second tier covers the hole!