I am making a 2 tier sponge cake so the top tier will be resting directly on the BC of the bottom tier, therefore need a good crusting BC. I want one that is all butter, no shortening. Has anyone got any good recipes please???

Um, did you know that if you sprinkle powdered sugar on the bottom tier where your cake board will be, no icing (crusting or otherwise) will come up on the cake board when the top tier is removed for serving?