Lloyd swears by this method for consistently perfect bars: Butter the pan, line it with foil (which is easier to work with than parchment paper—just use a good quality foil, like Reynolds, but not a heavy-duty one). Butter the foil. Pour the batter in, bake and let it cool completely in the pan. Lift the foil out of the pan and lay the brownies or bars, still on the foil, on a cutting board. Then, use a big, heavy knife, such as a 10-inch chef's knife, to cut the brownies in one strong motion. (Using a long blade will ensure your lines stay straight.) For bar cookies that are filled—or even more dangerously, topped—with nuts and/or coconut, use a serrated knife, with a sawing motion. Lloyd likes a plastic lettuce knife (like this $6 version from OXO) because it cuts through layers, especially ones made from graham cracker crumbs, without breaking the pieces apart.