For the brownie loaf, preheat the oven to 325°F (163°C). Line a 9 x 5-inch loaf pan with parchment paper, leaving an overhang on the sides for easy removal.

In a large microwave-safe bowl, combine the butter and chocolate. Microwave in 20-second intervals, stirring with a rubber spatula until completely melted and smooth.

Add the granulated sugar and brown sugar. Using a hand whisk or the same rubber spatula, mix until combined. Add the eggs and egg yolks one at a time, whisking well after each addition. Add the vanilla extract and vigorously beat/whisk until the batter becomes smooth and glossy.

In a separate bowl, sift the flour, cocoa powder, baking powder, cornstarch, espresso powder, and salt. Mix everything gently until combined. Add the dry ingredients to the chocolate mixture and gently fold until just combined. Do not overmix.

Pour the batter into the prepared loaf pan and smooth the top with an offset or rubber spatula. Sprinkle the loaf with a handful of semi sweet chocolate chips.

Bake for 50–55 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs attached. Avoid overbaking for the fudgiest texture.

Remove the loaf from the oven, and allow it to cool on a wire rack for about 30-40 minutes. Then, run a knife along the sides of the pan to help loosen the loaf. Using the parchment paper, remove the loaf and allow it to continue to cool until just barely warm to the touch.

While the loaf continues to cool, work on the brown butter for the espresso frosting. To brown the butter, melt it in a light-colored saucepan over medium heat. Continue cooking, stirring frequently, until the milk solids turn deep golden brown and the butter smells nutty.

Immediately pour the butter, including all those glorious browned bits, into a heat-safe bowl and add the espresso powder- mix well. Let the butter cool completely before making the frosting.

Once cooled, add the browned butter and softened cream cheese to a large bowl. Using a hand mixer or stand mixer, beat until smooth. Then add vanilla and salt, then mix to combine. Gradually add the powdered sugar, mixing on low until incorporated. Increase to medium-high speed and beat for 2–3 minutes, until light and fluffy.

Once the loaf has cooled and the frosting is light and fluffy, spread the frosting evenly over the top. Slice and enjoy!