Preheat the oven to 350°F (175°C) and prepare a baking pan.
Melt the butter in a large mixing bowl.
Add sugar, eggs, and vanilla extract to the melted butter, and mix until well combined.
Sift together the flour, cocoa powder, baking powder, and salt in a separate bowl.
Gradually fold the dry ingredients into the wet mixture until just combined.
Stir in the chocolate chips and nuts (if using).
Pour the batter into the prepared baking pan and spread it evenly.
Bake for 25-30 minutes or until a toothpick inserted comes out with a few moist crumbs.
Allow the brownies to cool in the pan before cutting.
Cut into squares and enjoy your decadent brownies!
