Preheat the oven to 350°F (175°C).

Grease your 9x9-inch baking pan or line it with parchment paper.

Melt the butter in a microwave-safe bowl or on the stove.

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

Add the eggs and vanilla extract, mixing until well combined.

Incorporate the cocoa powder, flour, salt, and baking powder into the wet mixture.

Stir until just combined.

Gently fold in the chocolate chips if using.

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

Bake for 20 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.

Let the brownies cool in the pan for about 10 minutes, then transfer them to a cooling rack.

Once cool, cut into bite-sized squares and enjoy.