- 10 tablespoons unsalted butter
- 3 ounces semisweet chocolate, chopped
- 1 1/4 cups sugar
- 1/2 cup unsweetened cocoa powder
- 1/4 teaspoon salt
- 1 tablespoon instant espresso powder
- 1/2 teaspoon vanilla extract
- 1 teaspoon Kahlua liqueur
- 2 large cold eggs
- 1/2 cup flour
- 1/4 cup chopped walnuts
- 10 miniature marshmallows
- 1/4 cup white or dark chocolate chips
- Preheat oven to 350 degrees F (175 degrees C). Prepare an 8×8-inch pan by greasing and lining with parchment paper.
- Place butter, chocolate, sugar, cocoa, and salt in a large mixing bowl. Set over a saucepan of simmering water (or use a double boiler). Stir to combine until butter is melted and the mixture feels hot to the touch. Set aside and allow to cool to just warm.
- Stir in vanilla; add eggs one at a time, stirring vigorously after each addition. Mix in espresso powder and coffee liqueur. Add flour and combine. Continue to stir vigorously for about 40 strokes. Pour into a prepared baking pan. Top with chopped walnuts.
- Bake for 20 to 25 minutes, or until a toothpick inserted into the center of the brownie comes out with a few moist crumbs.
- Remove the brownie from the oven, top with marshmallows and chocolate chips. Return to the oven, turn off heat, and allow the topping to melt onto the brownie for 3-5 minutes in the still warm oven. Remove and cool completely on a wire rack before cutting.