I have been using the Wilton recipe and it seems to crust very quickly. When I try to smooth the icing (whether with a warm spatula or a cold one) I end up with a sticky mess that seems almost like marshmallow. I have to frost it fast and try to make it perfect the first time around. I have tried waiting and using a piece of parchment paper but as soon as I disturb the frosting, LOOK OUT! Should I add more water? More sugar? Less shortening? Brands of powdered sugar?