Combine flour, dry pudding mix and baking soda. Beat butter and sugar in large bowl with mixer until light and fluffy. Blend in egg, chocolate and vanilla. Gradually beat in flour mixture.
Shape dough into 2 (6-inch) logs. Roll, 1 at a time, in nonpareils until evenly coated. Wrap individually in plastic wrap. Refrigerate 1 hour or until firm.
Heat oven to 350ºF. Cut each roll into 27 slices. Place, 2 inches apart, on parchment-covered baking sheets.
Bake 8 to 10 min. or until cookies are slightly firm to the touch. Cool 1 min. on baking sheets. Remove to wire racks; cool completely.