Ingredients
8tbspunsalted butter
1cupall-purpose flour,spooned and leveled
¼cupcocoa powder,unsweetened
½tspbaking powder
½tspsalt
8ozsemisweet chocolate,or bittersweet chocolate
1¼cupssugar
3largeeggs
Preparation
Preheat oven to 350 degrees F. Line a 9×13-inch baking pan with parchment paper and grease with cooking spray. In a small bowl, whisk together flour, espresso, and salt.
Set a large heat-proof bowl over a saucepan of simmering water to create a double-boiler. Add 3 cups chocolate chips and butter to bowl. Stir occasionally until melted together. Remove bowl from heat, then whisk in sugar.
Add eggs one at a time, whisking for 1 minute after each egg, then add egg yolks and whisk for 1 minute more. Fold in flour mixture just until combined, then fold in remaining 1 cup chocolate chips.
Pour batter into prepared pan and smooth top. Bake until a toothpick inserted in middle comes out with a few moist crumbs, which will take about 28 to 30 minutes. Let cool in pan for 30 minutes before using parchment paper to remove from pan.
