PREHEAT oven to 350°F. Microwave unsweetened chocolate and butter in large microwaveable bowl on HIGH 2 min. or until butter is melted. Stir until chocolate is completely melted and mixture is well blended. Add sugar; mix well. Blend in eggs and vanilla. Add flour; mix well. Cover. Refrigerate 1 hour or until dough is stiff.

SHAPE dough into 2-inch balls; insert lollipop stick into top of each ball. Place, 2 inches apart, on greased baking sheets.

BAKE 8 min. or just until set. (Do not overbake.) Let stand on baking sheet 1 min.; transfer to wire racks. Cool completely. Melt white chocolate as directed on package. Drizzle over lollipops; decorate with sprinkles. Let stand until chocolate coating is firm.