preheat oven to 350. mix confectioners sugar and granulated sugar together in a small plate. paint egg white onto each rose petal with a small, soft brush, and then quickly place in sugar mixture and sprinkle more over the top to cover thoroughly. set onto cookie sheet lined with parchment paper. when all of the rose petals are coated, turn off oven and place cookie sheet inside. wait about an hour to allow them to puff up and then cool completely before removing and sealing in an airtight container.