Instructions:

1. Preheat oven to 350ºF.
2. Grease 2 9" x 13" baking pans and set aside.
3. In a double boiler, melt on medium to medium-low heat:
• 1 lb butter, unsalted
• 1 lb chocolate chips, semi-sweet
• 2 cup chocolate chips, semi-sweet
• 6 oz chocolate, unsweetened
4. Cool slightly.
5. In a large mixing bowl, mix together:
• 6 eggs, extra-large
• 1 TBS instant espresso , powder
• 2 TBS vanilla extract
• 2 ¹/₄ cup granulated sugar
6. Stir in the warm chocolate mixture and cool to room temperature.
7. In a separate bowl, whisk together:
• 1 cup all-purpose flour
• 1 TBS baking powder
• 1 tsp kosher salt
8. Add to cooled chocolate mixture.
9. In a small bowl, combine:
• 3 cup walnuts , diced
• 2 cup chocolate chips, semi-sweet
• ¹/₄ cup all-purpose flour
10. Add coated walnuts and chocolate chips to the chocolate batter.
11. Pour into the prepared pans.
12. Bake for about 30 minutes, or until tester just comes out clean.
13. Cool thoroughly, refrigerate well and cut into squares.