This may be a silly question, but I am pretty new to this! I rolled out a big piece of fondant to cover an 11X15X2 cake. Today it is pouring and humid so I needed to use quite a bit of powdered sugar to keep it from sticking. I got the fondant on the cake, but it is bright blue with splotches of powdered sugar all over it! How do I get rid of the powdered sugar?

Try brushing the PS off with a big soft brush (like a blusher brush), or a soft papertowel you wadded up several times to soften it up.

after the cake has set up a few minutes you can take a folded up viva paper towel and dampen it and gently brush the surface of the whole cake and then let it have 20 minutes to dry from it. The cornstarch will dissolve away.

light rub down with shortening and wipe off excess