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

Melt the butter in a medium saucepan over low heat. Remove from heat and stir in the granulated sugar until well combined.

Let the mixture cool slightly. Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.

In a separate bowl, whisk together cocoa powder, flour, salt, and baking powder. Gradually combine this with the wet ingredients, stirring until just mixed.

Pour the batter into the prepared baking dish, spreading evenly. Bake for 20-25 minutes or until a toothpick inserted in the center comes out with moist crumbs.

Remove from the oven and let cool in the pan. Once cool enough to handle, cut into squares and enjoy!