Mix butter, sugar and egg.
Stir in flour, cocoa and salt.
Cover; chill 1 hour.
Divide dough in half; shape each half into roll, 1 1/2 inches in diameter.
Roll in nuts.
Wrap; chill 8 hours.
Heat oven to 400Â°.
Cut rolls into 1/8-inch slices.
Place 1 inch apart on ungreased baking sheet.
Bake about 8 minutes.
Immediately remove from baking sheet; cool.
Frost with Fudge Frosting.