Preheat your oven to 350°F (175°C). Butter an 8x8-inch baking pan and line with parchment paper, leaving an overhang for easy removal. prep

In a medium saucepan, melt butter over medium heat until it begins to sizzle. Remove from heat and whisk in chopped chocolate and espresso powder until fully melted and smooth. mix

Add granulated sugar to the melted butter-chocolate mixture. Whisk to combine; the mixture will appear grainy, which is normal. mix

Whisk in eggs one at a time, ensuring each is fully incorporated before adding the next. Stir in vanilla extract, vegetable oil, cocoa powder, and salt. mix

Gently fold in the flour, mixing until the batter is smooth with no streaks. Be careful not to overmix. mix

Pour the brownie batter into the prepared baking pan and spread into an even layer. Bake for 27-32 minutes, or until a toothpick inserted comes out with fudgy crumbs but no liquid batter. Allow the brownies to cool completely in the pan. bake

In a wide, shallow bowl, mix together boiling water, espresso powder, and sugar until dissolved. Let the mixture cool to room temperature. prep

Quickly dip each ladyfinger into the cooled coffee soak for about 1 second, then arrange them on top of the cooled brownies. Be careful not to let the ladyfingers sit too long in the liquid. assemble

In a large mixing bowl, whisk together mascarpone cheese, powdered sugar, and vanilla extract until smooth. Slowly add heavy cream, a few tablespoons at a time, and mix until fully combined. Once all the cream is added, increase mixer speed to high and whip for 1-2 minutes, or until stiff peaks form. mix

Spread the whipped mascarpone cream over the soaked ladyfingers in an even layer. Chill the brownies in the refrigerator for at least 1 hour, or until the topping is firm. finish

Use the parchment paper overhang to lift the brownies out of the pan. Dust with cocoa powder, slice into 9 large squares, and serve. finish