fudgy brownie recipe

**Ingredients:** - 1/2 cup unsalted butter - 1 cup granulated sugar - 2 large eggs - 1 teaspoon vanilla extract - 1/3 cup unsweetened cocoa powder - 1/2 cup all-purpose flour - 1/4 teaspoon salt - 1/4 teaspoon baking powder - 1/2 cup semi-sweet chocolate chips (optional, for extra gooeyness)