- Preheat oven to 350°F (180°C). In bowl, cream together butter, both sugars, egg yolk and vanilla until smooth.
- Stir in flour, baking soda and salt until just combined. Mix in chocolate and walnuts (if using).
- Drop 4 equal mounds dough on parchment paper-lined baking sheet, about 2 in. (5 cm apart). Bake 12 min., or until golden.
- Cool on baking sheet 2 min. then transfer to wire rack to cool completely.
Substitute pecans for walnuts.