I found a recipe online (http://www.delish.com/cooking...) that calls for 5 cups of powdered sugar to make the frosting. I'm not a baker, but this seems excessive to me. I surfed around and found numerous frosting recipes that call for anywhere from 1-4 cups of powdered sugar, but none of them call for 5 cups. Tomorrow is my grandson's birthday so I only get one shot at making this cake for him and I really don't want to screw it up and disappoint him. I can add the powdered sugar gradually and maybe only use two or three or four cups but I have no idea what to look for to tell me when I've added the right amount. Any suggestions would be greatly appreciated!