Preheat oven to 350 degrees

Line a 10×15 baking pan with parchment paper, leaving a slight overhang on all sides

Melt butter and chocolate in a heatproof bowl set over a pot of simmering water, stirring until smooth

Remove from heat, and whisk in sugar

Whisk in eggs, one at a time, until combined

Whisk in cocoa and salt

Fold in flour until combined

Pour batter into pan and spread batter along edges

Bake until set and a toothpick inserted into the center comes out with moist crumbs, 35 to 40 minutes

Let cool slightly in pan, about 15 minutes

Lift brownies from pan using parchment

Remove parchment and transfer to a wire rack

Let cool completely

If you prefer a more cake-like brownie, you can use Thomas’s cake-like brownie recipe.