Preheat oven to 350°F (175°C). Grease and flour a 9x13 inch baking pan.
In a large bowl, cream together the melted butter and sugar until well combined. Beat in the eggs one at a time, then stir in the vanilla.
Combine the flour, cocoa, baking powder, and salt. Gradually add to the wet ingredients and mix until just combined. Stir in the chocolate chips.
Pour batter into prepared pan and spread evenly. Bake for 20-25 minutes, or until a toothpick inserted into the center comes out with moist crumbs. Let cool completely before cutting into squares.
Notes
Enjoy these Brookies warm or at room temperature. They are best served fresh!