Preheat oven to 350°F (175°C) and grease an 8x8 inch square baking pan or line with parchment paper.

In a large mixing bowl, whisk together the melted butter and granulated sugar until fully incorporated.

Add the eggs and vanilla extract to the butter mixture; whisk vigorously for approximately 2 minutes until the batter lightens in color and becomes smooth.

Sift the cocoa powder, flour, salt, and baking powder into the bowl.

Gently fold the dry ingredients into the wet mixture using a rubber spatula until just combined; do not overmix.

Stir in the chocolate chips until evenly distributed.

Pour the batter into the prepared baking pan and level the surface with a spatula.

Bake for 22 to 25 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs attached.

Remove from the oven and allow the brownies to cool completely in the pan before slicing into 16 squares.