To make flower petals, cut mini marshmallows in half on a diagonal. This will expose a sticky inside. Press the sticky side into the colored sugar. I make a lot of red ones for the flower and a few green ones for leaves around the edge.
Press the sugared marshmallows into the frosting working around the outside edge. Then make another circle of marshmallows inside that forming a flower. Continue until top is covered. Sprinkle colored sugar or other sprinkles into center, if desired.