You want to start by preheating the oven to 350 degrees Fahrenheit. Afterward, in an 8×12” baking pan, grease with cooking oil spray then line it with parchment paper then set aside.
Mix melted butter and brown sugars in a medium-sized bowl. Whisk until the mixture becomes homogeneous. Gently add the eggs, then add the vanilla extract whisk until it is lighter in color.
In a bowl, sift in the flour, salt, and cocoa powder. Delicately fold the dry ingredients into the wet ingredients until it is combined. Make sure not to overbeat because doing so will affect the texture of your brownies.
Little by little add the chopped chocolate or chocolate chips, pour batter into the prepared pan, smoothing the top out evenly, and top it with remaining chocolate pieces.