Preheat your oven to 350°F (175°C) and line a 9×13-inch baking pan with parchment paper.

In a large mixing bowl, combine the granulated sugar, brown sugar, and melted butter. Whisk until well combined. Add the eggs one at a time, mixing well after each addition, then stir in the vanilla extract.

In another bowl, mix the flour, cocoa powder, baking powder, and salt.

Gradually fold the dry ingredients into the wet mixture. Be careful not to overmix.

Pour in the cooled brewed coffee and gently mix until just combined.

Pour the brownie batter into the prepared pan and spread it evenly. Bake for 25-30 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs.

Once baked, allow the brownies to cool in the pan for about 15 minutes, then transfer to a wire rack.

In a mixing bowl, beat the softened butter until creamy. Add the powdered sugar and cocoa powder, mixing until combined.

Pour in the brewed coffee and vanilla, then continue mixing until the frosting is smooth and fluffy.

Spread the frosting evenly over the top of the completely cooled brownies.

Cut into squares and serve!