Preheat oven to 350°F and prepare a 9x12 baking pan by spraying generously with non-stick spray and parchment paper and set aside.
In a microwave safe bowl, add the butter and semi-sweet chocolate and heat in the microwave on 30 second increments, stirring in between, until melted and smooth. Set aside to cool.
In the bowl of a stand mixer equipped with a paddle attachment, add the sugar, eggs, and vanilla, and mix until well combined.
Pour in the cooled chocolate mixture and mix until well combined and smooth.
Sift in the flour, baking powder, espresso powder, and cocoa powder. Mix until just combined and there are no dry spots remaining.
Pour batter into the prepared baking pan and smooth evenly. Bake for 40-45 minutes or until a toothpick inserted in the center of the brownies comes out with a few moist crumbs.
Remove from the oven and allow to cool completely on a wire rack.