Preheat your oven to 350F and generously grease an 8x8 inch baking pan. Line it with parchment paper for easy removal.
Melt the unsalted butter in a large microwave safe bowl.
Whisk the sweetened condensed milk, milk and vanilla extract into the melted butter until the mixture is completely smooth and glossy.
Sift the all-purpose flour, unsweetened cocoa powder and baking powder directly into the wet ingredients. Gently fold the batter together with a rubber spatula until no dry spots remain.
Take your time with this step to avoid overmixing, which can make the brownies tough instead of fudgy. Stir in the dark chocolate chips gently so they are spread throughout the thick batter.
Pour the brownie batter into your prepared pan and smooth the top with your spatula.
Bake for 25 to 30 minutes, or until a toothpick inserted in the center comes out with moist crumbs.
Allow the brownies to cool completely in the pan before slicing them into neat squares.
