Preheat oven to 350°F. Line a 9x13" pan with foil and spray with nonstick cooking spray.
Melt butter in a saucepan over medium heat. Cook, stirring often, about 6 minutes, until it becomes brown in color. It will foam, reduce, then foam again. Once it’s done cooking the foam is a light brown and it will dissipate after you remove it from the heat. Once it starts to brown, keep stirring so it doesn’t burn. Once it gets to an amber color, turn off the flame.
Add baking chocolate to the butter and stir until the chocolate is melted. Stir in sugar, eggs, vanilla, salt, and cocoa and stir until combined. Stir in flour then stir in chocolate chips
Pour brownie batter into prepared baking pan. Bake for 25-35 minutes until a toothpick along the edge comes out with just a few crumbs. This results in very fudgy gooey brownies. Cool before slicing into bars.