1 cup unsalted butter, +some softened butter for the pan
2/3 cup flour +a little more for the pan
2 cups sugar
4 large eggs
1/2 tsp vanilla extract
3/4 cup cocoa powder
1/2 tsp baking powder
1/2 tsp salt
Preheat oven to 350 degrees
Butter and flour a 9×9 inch metal baking pan, tapping out the excess flour.
Melt the butter in a medium saucepan over medium heat.
Remove the pan, and mix in the sugar. Add the eggs and vanilla, and mix well.
Add the flour, cocoa, baking powder, and salt, and stir until the batter is smooth, about 1 minute.
Spread the batter into the baking pan, smoothing it to fill the pan evenly. Bake for about 40 minutes, or until a toothpick inserted into the center comes out with a few moist clumps clinging to it.
Remove the pan from the oven, and cool the brownies in the pan on a rack.