Hi Lois! Great questions! If you going to be cutting circles out of a sheet cake, we would recommend flipping the cake out of the pan first onto a piece of parchment. Then, you can cut the circles that are needed and you will be able to handle to cake a bit easier. Some bakers will also freeze the cake first (for 15-20 minutes) or pop it in the fridge before cutting to help firm up the cake itself. And for the uneven batter in a cake pan, there are few tips that can be useful here. Depending on the type of batter being made, you can gently tap the sheet pan on a work surface to help even out the batter. Using a thin, long, offset spatula can also come in handy when spreading larger distances. If you find that your oven is hotter on one side, that can cause one side of the cake to rise up a bit more...rotating larger baking sheets during the baking process can help even that out. 

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