Combine dark chocolate and butter in a medium microwave-safe bowl and melt on HIGH heat in 30 second bursts, stirring after each interval until smooth, about 1½ to 2 minutes (see the Recipe Notes for using the stovetop). Allow the mixture to cool for 5 minutes.
Whisk in the granulated and brown sugar, then the eggs (one at a time), and finally the vanilla.
Fold in the flour mixture just until combined (do not overmix). Fold in the chocolate chips.
Bake the brownies for 28 to 30 minutes or until a cake tester or toothpick inserted in the center comes out clean (or maybe with just a few crumbs attached). Once done, remove the brownies from the oven and cool completely in the pan on a wire rack.
Carefully lift parchment to remove the brownie slab from the pan and place it on a cutting board. Cut it into 2-inch squares with a sharp knife, wiping off the knife between cuts.
Serve with a large glass of milk (or your favorite non-dairy alternative) and enjoy!
You can use regular unsweetened cocoa powder if you prefer. The brownies just won’t have as deep a chocolate flavor.Adding espresso powder to the brownie batter helps deepen the chocolate flavor. It’s optional, but highly recommended.For slightly thinner brownies, use a 9- x 9-inch inch baking pan. Reduce the baking time by about 5 minutes.If you prefer to use your stovetop, just melt the dark chocolate and butter in a heavy saucepan over low heat, stirring until smooth.