Transfer the mixture to the prepared pan. Place a large piece of parchment paper, wax paper, or plastic wrap atop the bar mixture and use it to spread, flatten, and very firmly press the mixture evenly into the pan. Discard the paper or plastic.☞ TESTER TIP: To make the mixture even less likely to stick to the paper or plastic wrap, you can spray the bottom side of it with nonstick vegetable spray.