Brownie pan

Photo: Dorling Kindersley/Thinkstock

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Mistake #3: Using Any Old Pan
You may not think an inch could make that much of a difference in a baking pan, but Helding says it's more critical than many of us realize. If the recipe says to use an 8-inch square pan and you use a 9-inch, the batter will cover a bigger area. Thinner brownies cook faster, so if you don't adjust the baking time (i.e., pull them out a few minutes early), they could burn. There's no need to go out and buy a new pan though, Helding says, just know that smaller pans make thicker brownies, so bake longer when using one; while larger pans make thinner brownies, so bake for less time when using one of those.