Step 1: Preheat oven to 350 degrees and line a 9 x 9-inch pan with parchment paper. I use some sort of clip to hold the parchment paper in place and remove them after the batter is ready for the oven.
Step 2: Beat softened butter, brown sugar, and granulated sugar with a stand or hand mixer until combined. Add the wet ingredients: eggs, vanilla extract, and milk.