- 1/2 cup (1 stick) unsalted butter plus more for foil
- 8 ounces semisweet chocolate chopped
- 1 ¼ cups sugar
- 3/4 teaspoon salt
- 3 large eggs
- 3/4 cup all-purpose flour (spooned and leveled)
- 1 cup chopped walnuts or pecans (optional)
- Preheat oven to 350°. Line bottom and sides of an 8-inch square baking pan with foil; butter foil. Set aside.
- Place butter and chocolate in a medium heatproof bowl set over (not in) a saucepan of simmering water; stir frequently, until almost melted. Remove from heat; stir until completely melted.
- Whisk in sugar and salt until smooth; whisk in eggs. Gently whisk in flour just until smooth (do not overmix). Fold in nuts, if using.
- Spread batter evenly in prepared pan. Bake until a toothpick inserted in center comes out with a few moist crumbs attached (they should form a ball when rolled between your fingers), 45 to 50 minutes. Cool completely in pan.
- Use foil to lift from pan; peel off and discard. Cut into 16 squares.
Tips/TechniquesNote: Instead of dipping the dry measuring cup into the flour, spoon flour into the cup; then level flour with the straight edge of a knife.