Preheat oven to 350 F. In a large bowl, whisk together flour, sugar, cocoa powder, salt and baking powder.
Add in melted butter, melted chocolate, eggs and vanilla extract. Whisk together until smooth.
Gently fold in chocolate chips with a spatula. Spread the brownie batter into a greased 9x13-inch baking pan. Bake for 30-35 minutes.