Aww Karen, thanks for the shout-out!
Modeling chocolate panels make for incredibly sharp corners on square cakes, but if you must use fondant, I find running 2 fingers along the edge – one finger on the top, one finger on the side. As your fingers meet at that 90 degree angle it will “pinch” the fondant and make a sharp crease / edge. Hope that helps!!
Jenniffer White, Cup a Dee Cakes - http://cupadeecakes.blogspot.com
