Mix peanut butter, sugar and egg until blended. Refrigerate 30 min.
Roll peanut butter mixture into 18 balls. Place, 3 inches apart, on baking sheets. Flatten each ball, in crisscross pattern, with fork.
Bake 18 to 20 min. or until lightly browned. Cool on baking sheets 5 min. Remove to wire racks; cool completely.
Cover baking sheet with parchment or waxed paper. Melt chocolate as directed on package. Partially dip cookies in chocolate; gently shake off excess chocolate. Dip cookies in nuts; place on prepared baking sheet. Refrigerate until chocolate is firm.