Prepare waffle mix according to package instructions.
Spray the waffle iron with nonstick cooking spray on both plates. Scoop 1/3 cup brownie batter onto the center of the waffle iron and close the lid. (If you have a large waffle maker with four square sections, use 1/4 cup per square.)
Cook for 5 to 7 minutes, until the waffle iron stops steaming.
Carefully remove the waffles from the waffle iron and allow to cool completely before serving.