Preheat your oven to 350°F (175°C) and grease a 9x9-inch baking pan.
Melt the butter in a medium saucepan over low heat.
Remove from heat and stir in sugar, eggs, and vanilla.
Add cocoa powder, flour, salt, and baking powder; stir until combined.
Fold in chocolate chips if using.
Spread the batter into the prepared pan evenly.
Bake for 20-25 minutes, or until a toothpick inserted comes out with a few moist crumbs.
Let the brownies cool in the pan for at least 10 minutes.
Cut into squares and serve warm or at room temperature.
Enjoy your fudgy brownies with a scoop of ice cream or a dusting of powdered sugar!