Heat oven to 350°F. Grease baking sheet.Advertisement
In bowl, beat butter, vanilla, both sugars and espresso on high speed until fluffy, 4 minutes. On low, add eggs; beat well. Add flour, cocoa and salt; beat until blended. Add nuts and chocolate; mix just until smooth.
Bake in 350°F oven 10 minutes or until barely set. Let cookies cool on pan on wire rack 2 minutes. Transfer cookies to rack; let cool. Store in airtight container for up to 3 days.