Stupid Nest ate my post!
Happy Birthday!
I havent tried the powdered sugar thing. Theortically, I think it could work as much as it could be a problem. (I'm not going to write a bunch of detail in case it gets deleted again.)
Parchment works for any flat bottom baking pan. Just cut a piece to the right size. No need to butter or flour the pan or the parchment. Just run a metal spatula or butter knife around the edge after baking. For bar cookies/brownies, cut a piece slightly larger than the pan length wise. Use the parchment handles to lift the brownies out when they are done.