Preheat the oven to 350°F (175°C) and grease a 9x9 inch baking pan.
In a medium saucepan, melt the butter over low heat. Remove from heat and stir in sugar, eggs, and vanilla extract until well combined.
In a separate bowl, sift together flour, cocoa powder, baking powder, and salt. Gradually add the dry ingredients to the wet mixture, stirring until just combined.
Fold in the chocolate chips (semi-sweet, white, and milk) until evenly distributed in the batter.
Pour the batter into the prepared baking pan and spread it evenly.
Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted in the center comes out with moist crumbs (do not overbake).
Allow the brownies to cool in the pan for 10 minutes before transferring to a wire rack to cool completely.
Cut into squares and serve warm or at room temperature. Enjoy the triple chocolate goodness!