Making dessert bars is a usually a fairly simple process, but when it comes to cutting the bars into neat, even squares, things quickly become more complicated. Often, despite your best efforts to cut the bars perfectly, they end up in crooked, uneven shapes with messy, raggedy edges.
Line the baking pan with aluminum foil or parchment paper before you pour the batter in the pan. Use enough foil or parchment paper to fold at least 1 to 2 inches over each side of the pan.
Coat the foil lightly with cooking oil or nonstick cooking spray if the recipe directs you to grease the pan. Aluminum foil makes the bars easier to remove from the pan without tearing them, and makes clean-up easier.
Pour the batter in the pan and bake as directed in your recipe.
Remove the bars from the oven and allow them to cool slightly. Using a ruler as a guide, score the top of the bars very lightly with the tip of a paring knife.
Place the bars in the freezer for a few minutes until the bars are slightly firm.
Remove the bars from the freezer. Lift the edges of the aluminum foil or parchment paper, then lift the bars out of the pan. Place the bars on a cutting board
Dip a serrated plastic knife in hot water, then cut the bars along the scored lines, using a sawing motion. Dessert bars usually don't adhere to plastic and as a result, cutting is neater.
Serve the bars or store them in an airtight container.