Preheat your oven to 350°F (175°C).

Grease your 8x8-inch baking pan or line it with parchment paper.

In a large bowl, whisk together the melted butter and granulated sugar until smooth.

Add the eggs, one at a time, mixing well after each addition, then stir in the vanilla extract.

In another bowl, sift together the flour, cocoa powder, baking powder, and salt.

Gradually add the dry ingredients to the wet mixture, stirring until just combined.

If using, gently fold in the chocolate chips.

Pour the brownie batter into the prepared pan and smooth the top.

Bake for 25 minutes, then check for doneness; a toothpick should come out with moist crumbs.