HEAT oven to 325°F. Line 13x9-inch pan with foil, with ends extending over sides. Mix crumbs, 1/2 cup nuts and butter; press onto bottom of pan. Refrigerate until ready to use.

BEAT cream cheese and sugar in large bowl with mixer until blended. Add sour cream, flour and vanilla; mix well. Add eggs, 1 at a time, mixing on low speed after each just until blended. Pour over crust.

BAKE 45 min. or until center is almost set. Cool. Refrigerate 4 hours. Use foil handles to lift cheesecake from pan. Drizzle with topping; top with remaining nuts. Let stand until topping is set.