serves makes one 8- by 8-inch pan, active time 20 minutes, total time 45 minutes
- 7 tablespoons (3 1/2 ounces) unsalted butter
- 8 ounces 70% bittersweet chocolate, finely chopped
- 1 teaspoon instant espresso powder
- 1/4 teaspoon salt
- 3/4 cup (5 1/4 ounces) granulated sugar
- 1/4 cup (1 3/4 ounces) packed light brown sugar
- 2 large eggs
- 1 1/2 teaspoons vanilla extract
- 1/2 cup (2 1/2 ounces) all purpose flour
- 1/2 cup roasted cashews, chopped
- Adjust rack to middle position and preheat oven to 350°F. Line bottom and two sides of an 8- by 8- inch baking pan with foil, allowing edges to overhang the sides. Grease the pan.
- In a large heatproof bowl set over a pan of barely simmering water, heat butter, chocolate, espresso powder, and salt until melted and smooth.
- Remove from heat and let cool 5 minutes. Whisk in sugars until combined. Add eggs, one by one, whisking well after each addition. Add vanilla and mixture for one minute.
- Add flour to chocolate and whisk until combined and mixture is smooth and glossy (see note). Stir in cashews. Spread into pan and bake until just set and top is crusty, about 25 minutes. Transfer pan to wire rack to cool before cutting into squares.