1. Preheat oven to 325°. Line bottom and sides of a 9-inch springform pan with aluminum foil, allowing 2 to 3 inches to extend over sides. Stir together 1 1/2 cups cookie crumbs and butter; press firmly onto bottom of prepared pan.
2. Beat cream cheese at medium speed with an electric mixer until smooth. Add sour cream, sugar, and vanilla, beating well. Add eggs, 1 at a time, beating at low speed just until blended after each addition. Pour into prepared crust.
3. Microwave chocolate morsels in a microwave-safe glass bowl at HIGH 1 1/2 minutes or until smooth, stirring at 30-second intervals. Pour melted chocolate onto center of cheesecake batter. Swirl chocolate into batter using a small spatula. (Do not overstir.)
4. Bake at 325° for 1 hour and 10 minutes to 1 hour and 15 minutes or until center is almost set. Cool on a wire rack 1 hour or until completely cool. Cover and chill at least 8 hours or up to 24 hours. Gently run a knife around outer edge of cheesecake to loosen; remove sides of pan and foil. Let stand for 30 minutes before serving. Sprinkle with remaining cookie crumbs.