Preheat the oven to 350°F (175°C)
Grease and line an 8×8-inch or 9×9-inch baking pan with parchment paper
Melt butter and chocolate together, or prepare your brownie batter according to the recipe
Whisk in sugar, then add eggs and vanilla
Stir in flour, cocoa powder, and salt until just combined
Fold in chocolate chips or nuts if desired
Pour the batter into the prepared pan and spread evenly
Bake for 20 to 30 minutes, or until a toothpick comes out with a few moist crumbs
Let the brownies cool in the pan
Lift out and cut into squares