Preheat oven to 350°F (175°C). Grease an 8-inch square baking pan with butter.
In a medium bowl, beat butter and sugar until light and fluffy. Add eggs one at a time, beating well after each addition.
Stir in vanilla extract. In a separate bowl, sift together cocoa powder, baking powder, salt, and flour. Gradually stir dry ingredients into wet ingredients until just combined.
Stir in chocolate chips. Spread batter evenly into prepared baking pan. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean.
Allow brownies to cool before cutting into squares.
Interesting Facts
Brownies are a popular treat in the United States, but their roots can be traced back to England in the late 1800s.
Brownies are traditionally made with cocoa powder, giving them a deep, chocolate flavor.
Adding chocolate chips to brownies makes them extra fudgy and delicious.