Preheat your oven to 350°F (175°C) and prepare an 8-inch baking dish with non-stick spray or parchment paper.

Melt the unsalted butter in a microwave-safe bowl for 30-45 seconds and let it cool in a large mixing bowl.

Combine granulated sugar, eggs, and vanilla extract with the melted butter, whisking until slightly fluffy for about 2-3 minutes.

Sift in all-purpose flour, unsweetened cocoa powder, baking powder, and salt, mixing gently until smooth.

Pour the brownie batter into the prepared baking dish and bake for 30-35 minutes until a toothpick comes out clean.

Cool the brownies in the pan for 10-15 minutes, then transfer to a wire rack to cool completely.

Dissolve instant coffee granules in heavy whipping cream and set aside for the frosting.

Beat unsalted butter until light and fluffy for about 3-4 minutes, preparing for the frosting.

Slowly mix in sifted powdered sugar and the coffee-infused cream until desired frosting consistency is reached.

Spread the coffee frosting generously over the cooled brownies, slice, and serve.