Preheat your oven to 350°F (175°C) and line an 8"x8" metal baking pan with parchment paper.

In a microwave-safe bowl, combine unsalted butter and chopped semi-sweet chocolate. Microwave in 15-second intervals until melted and smooth.

Whisk in both granulated and light brown sugar until well combined.

Add room temperature large eggs and vanilla extract to the mixture. Whisk until smooth and glossy.

Gently fold in all-purpose flour, cocoa powder, espresso powder, and fine sea salt until just combined.

Spread the brownie batter evenly into the prepared pan and bake for 30-35 minutes.

Let the brownies cool completely in the pan on a wire rack for about 1 hour.

In a small saucepan, heat heavy cream until just simmering, pour over chopped chocolate, and let sit for 2 minutes.

Stir the ganache until smooth, cool to room temperature, then whip until light and fluffy.

Cut the cooled brownies into 16 mini bites and pipe the whipped ganache on top.