Spread the batter in the lined pan, then use a knife to make light swirls in the top of the batter. Bake on the lower rack for about 25 minutes, until a toothpick inserted in the center comes out almost clean. Cool the brownies in the pan on a baking rack.
Once the brownies are completely cool, lift the edges of the parchment paper and transfer the brownies to a cutting board. Use a sharp chef's knife to cut the brownies into 16 or 25 squares