Preheat the oven to 350°F.
Line an 8x4 inch aluminized steel loaf pan with parchment paper and set aside. See video for guidance on how to line a loaf pan with parchment paper. (Note: this recipe was not tested in a glass loaf pan).
Melt the bittersweet chocolate and butter in a microwave safe glass bowl in the microwave in 30 second increments until melted and smooth.
2 oz. bittersweet chocolate, chopped, 6 Tbsp. unsalted butter
Stir in the cocoa powder until smooth and set aside.
1/4 cup Dutch process cocoa powder
Using a stand mixer fitted with the whisk attachment or hand held mixer, beat the brown sugar, eggs, vanilla, espresso powder, and salt for 5-7 minutes or until thick and pale in color.
3/4 cup light brown sugar, packed, 1 large egg, room temperature, 1 large egg yolk, room temperature, 1/2 tsp. vanilla extract, 1/2 tsp. espresso powder (optional), pinch of salt
Stir in the melted chocolate butter mixture.
Fold in the flour and chocolate chips just until combined.
1/4 cup all purpose flour, 3 Tbsp. chocolate chips
Pour into the prepared pan and bake for 25-27 min or until a toothpick inserted in the middle comes out mostly clean. A few crumbs are OK.
Let the brownies cool in the pan for about 10 minutes. Then use the parchment paper to lift the brownies from the pan.
Once cool enough to cut, slice into 8 brownies. Garnish with flaky sea salt and enjoy!
flaky sea salt, for garnish