Instructions

• Position an oven rack in the lower third of the oven and preheat to 325°F.
• Line an 8-inch square pan with parchment paper or aluminum foil, leaving an overhang for easy removal, and spray the lining lightly with nonstick cooking spray.
• In a large heatproof bowl (glass preferred), combine 10 tablespoons unsalted butter, 1 1/4 cups sugar, 3/4 cup plus 2 tablespoons unsweetened cocoa powder, and 1/2 teaspoon salt.
• Set the bowl over a pan of water that is just barely simmering (bain-marie). Stir occasionally until the butter is fully melted and the mixture is smooth and combined.
• Remove the bowl from the heat and let the mixture cool for 5–10 minutes so it is not too hot when you add the eggs.
• Stir in 1 teaspoon pure vanilla extract.
• Add 2 large eggs one at a time, beating vigorously after each egg until fully incorporated.
• In a separate bowl, stir together 1/2 cup all-purpose flour and 1 teaspoon baking powder until evenly combined.
• Add the flour mixture to the chocolate batter and stir vigorously to combine — about 40 strokes with a spoon is a good guide.
• If using, fold in 1/2 cup chocolate chips and/or 1/2 cup chopped walnuts until distributed evenly.
• Pour the batter into the prepared pan and smooth the top with a spatula.
• Bake for 30–35 minutes, or until a tester inserted into the center comes out with moist crumbs attached (not wet batter).
• Cool the brownies in the pan on a wire rack. When cooled, lift from the pan using the parchment/foil overhang, cut, and serve.
• If not eating the same day, wrap or cover the brownies tightly before storing.