Preheat your oven to 350°F (175°C) and grease a 9x13-inch baking pan.
In a large bowl, combine melted butter and sugar; mix until smooth.
Add eggs one at a time, mixing well after each addition.
Stir in vanilla extract.
In a separate bowl, whisk together flour, cocoa powder, baking powder, and salt.
Gradually add dry ingredients to the wet ingredients, mixing until just combined.
Fold in chocolate chips.
Pour the batter into the prepared baking pan and spread evenly.
Bake for 25-30 minutes, or until a toothpick comes out clean.
Allow brownies to cool before frosting.