Servings: 24 pieces
1 package (21 to 24 ounces) brownie mix
1 1/2 tablespoons espresso powder or freeze-dried coffee
2 tablespoons boiling water
3/4 cup sour cream
1/4 cup butter, melted
1/2 cup whipping cream
1/4 cup powdered sugar
1/2 teaspoon vanilla
1 cup (8 ounces) mascarpone cheese, softened to room temperature
For the brownies, preheat the oven to 350° F
Grease the bottom only of a 13x9-inch baking pan. Place the brownie mix in a large bowl. Dissolve the espresso powder in boiling water; add to the bowl. Add the sour cream, butter, and eggs; mix well. Spread the batter into the prepared pan. Bake for about 25 minutes, or until the brownies begin to pull away from the sides of the pan, and the center is just set (do not overbake). Transfer the pan to a wire cooling rack; cool completely.
For the topping, beat the whipping cream with an electric mixer on medium-high speed until soft peaks form. Beat in the sugar and vanilla. Add the cheese in two batches; beat until smooth and fluffy. Cover and refrigerate until serving time.
To serve, cut the brownies into squares, and serve with the whipped topping.