In a medium saucepan, melt the butter over medium heat. Once melted, remove from heat and let cool slightly.
Stir in the granulated sugar until well combined.
Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.
In a separate bowl, whisk together the flour, cocoa powder, salt, and baking powder.
Gradually add the dry ingredients to the butter and sugar mixture, stirring until just combined.