2In large bowl, beat butter, sugar, eggs, and vanilla until light and fluffy. Combine the flour, cocoa, baking soda, and salt; stir into the butter mixture until well blended. Mix in the chocolate chips and walnuts. Drop by rounded teaspoonfuls onto ungreased cookie sheets.
3Bake for 8 to 10 minutes in the preheated oven, or just until set. Cool slightly on the cookie sheets before transferring to wire racks to cool completely.
Aluminum foil can be used to keep food moist, cook it evenly, and make clean-up easier.