Slightly adapted from Ina Garten
1 lb unsalted butter
1 pound plus 12 oz semisweet chocolate chips
6 oz unsweetened chocolate
3 tablespoons instant espresso granules
4 tablespoons vanilla extract
2 1/4 cups cane sugar
1 1/4 cups all-purpose flour
1 tablespoon baking powder
1 teaspoon sea salt
3 cups chopped walnuts
- Heat oven to 350F°. Butter and flour a 12 x 18 x 1-inch baking pan.
- Melt together the butter, 1 lb chocolate chips, and the unsweetened chocolate in a medium bowl over simmering water. Cool slightly. In a large bowl, stir together the eggs, espresso granules, vanilla, and sugar. Stir the warm chocolate mixture into the egg mixture and cool to room temperature.
- In a medium bowl, whisk together 1 cup of flour, baking powder, and salt. Add to the cooled chocolate mixture. Toss the walnuts and 12 oz of chocolate chips in a medium bowl with 1/4 cup of flour, then add them to the chocolate batter. Pour into the baking sheet.
- Bake for 35 minutes. Don’t overbake. Cool thoroughly, refrigerate, and cut into squares.