Preheat oven to 350 degrees Fahrenheit (175 degrees Celsius). Coat a nine-inch (23-centimeter) pan with cooking spray. You can use a 9 x 13-inch (23 x 33-centimeter) pan

for thinner brownies.

In a large bowl, combine flour, choice of sugars, cocoa, and baking powder. Add eggs, oil, and vanilla; beat by hand or machine until a smooth, slightly runny batter forms.

Spread evenly into the prepared pan. If desired, top with chocolate chips, cacao nibs, coconut flakes, nuts, or your favorite combination.

Bake for 35–40 minutes on the center rack. Cool completely before slicing.