PREHEAT oven to 375° F.
BEAT butter, sugar, vanilla extract, lemon zest and salt in large mixer bowl until creamy. Gradually beat in flour; stir in morsels and nuts. Shape level tablespoons of dough into 1 1/4-inch balls. Place on ungreased baking sheets.
BAKE for 10 to 12 minutes or until cookies are set and lightly browned. Remove from oven. Sift powdered sugar over hot cookies on baking sheets. Cool on baking sheets for 10 minutes; remove to wire racks to cool completely. Sprinkle with additional powdered sugar, if desired. Store in airtight containers.