Ingredients:
- For the brownies:
- 3 cups lightly packed dark brown sugar
- 1 cup (2 sticks) unsalted butter, at room temperature
- 8 extra-large eggs
- 1 tablespoon pure vanilla extract
- 1/8 teaspoon fine sea salt
- 1 1/2 cups all-purpose flour
- 2/3 cup Dutch-processed cocoa powder
- 2 tablespoons instant espresso powder
- 2 cups toasted nuts, such as a mixture of pecans, walnuts, and hazelnuts, chopped
- 2 cups semisweet chocolate chips
- For the frosting:
- 1 1/4 cups superfine sugar
- 2 tablespoons instant espresso powder
- 1/4 cup Cognac
- 1/4 cup whole milk
- 6 tablespoons unsalted butter
- 1 cup semisweet chocolate chips