Preheat oven to 350F. Melt 1/2 cup chocolate chips over hot water or in microwave. Stir until smooth; cool to room temperature. In small cup, dissolve coffee in boiling water; set aide. Combine flour, soda, and salt; set aside.
In large bowl, combine butter, sugars and coffee; beat until creamy. Add egg and melted chocolate; mix well. Gradually add flour mixture. Stir in remaining 1-1/2 cups chocolate chips and walnuts.
Drop by rounded tablespoonfuls onto ungreased cookie sheets. Bake at 350F for 10-12 minutes. Let stand 2-3 minutes before removing from cookie sheets; cool completely.