Preheat your oven to 350°F (175°C) and grease a 9x13 inch baking pan.

In a large bowl, melt the butter, then whisk in the sugar until well combined and smooth.

Beat in the eggs one at a time, followed by the vanilla extract, ensuring each is fully incorporated.

In a separate bowl, combine the flour, cocoa powder, salt, and baking powder, then gradually add the dry ingredients to the wet mixture, mixing until just combined.

Stir in the chocolate chips, if using, distributing them evenly throughout the batter.

Pour the batter into the prepared baking pan and spread it evenly.

Bake for 25-30 minutes, or until a toothpick inserted into the center comes out with moist crumbs, but not wet batter.

Let the brownies cool completely in the pan on a wire rack before cutting and serving.