Preheat your oven to 325 degrees F. Line an 8-inch x 8-inch pan with parchment paper. Spray the pan and paper with non-stick cooking spray. Set aside.
In a small bowl, whisk together the granulated sugar, all-purpose flour, unsweetened cocoa powder, brown sugar, and salt. Set aside.
In a large bowl, whisk together the eggs, melted butter, and vanilla until smooth. Then add in the dry ingredients and stir with a rubber spatula or wooden spoon until you have a thick batter. Fold in 3/4 cup of the chocolate chunks.
Pour brownie batter into the prepared pan and smooth into an even layer with an offset spatula. Then sprinkle the remaining chocolate chunks on top.
Bake for 45 minutes or until a toothpick comes out almost clean and the top looks set.
Remove from the oven and cool completely on a wire rack. Cut into 16 squares (or however many brownies you want) and enjoy.
Notes
You can use chocolate chips or chocolate chunks for these brownies. Semi-sweet chocolate, dark chocolate, and milk chocolate will all work in this recipe.