I made a TX Sheet Cake (Yum) in a cheesecake pan. I'm not familiar at working with these. Stupidly, I put parchment in the bottom which I think helped me get the bottom plate out from under the cake. How can I get the parchment out? Any hints for doing this better next time? I used this pan because I wanted to contain the icing to the top of the cake. I achieved that goal. Help?