HEAT oven to 325°F.

MIX crumbs, 3 Tbsp. sugar and butter; press onto bottom of 9-inch springform pan. Bake 10 min.

MELT 4 chocolate squares as directed on package. Beat cream cheese and remaining sugar in large bowl with mixer until well blended. Add melted chocolate and extract; mix well. Add eggs, 1 at a time, mixing on low speed after each just until blended; pour over crust.

BAKE 45 to 50 min. or until centre is almost set. Run knife around rim of pan to loosen cake; cool before removing rim. Refrigerate 4 hours. Grate remaining chocolate square. Top cheesecake with Cool Whip, crushed candy and grated chocolate just before serving.