Grease the bottom and sides of the pan with butter. Then, cut a strip of parchment paper to the width of the brownie pan, letting the ends of the paper hang off. Press it into the bottom of the pan and make creases where the edges are. Trim some of the overhangs if necessary. You only need enough to lift the brownies out of the pan. The paper should not be long enough to fold back against the brownie batter while baking.