Make crumb crust with 1 cup chocolate wafer crumbs and 1/4 cup (1/2 stick) butter or margarine; press into bottom of 9-inch springform pan. Tip: to crush wafers put them in sealed plastic starage bag and crush with rolling pin.

Heat oven to 450F.

Beat cream cheese and sugar until blended. Add sour cream and vanilla and beat until blended. Beat in cocoa and flour; Add eggs, one at a time, beat just until blended. Pour onto crust.

Bake 10 minutes. Reduce oven temperature to 250F and continue baking 40 minutes. Remove from oven to wire rack. Loosen cake with knife from side of pan. Cool completely before removing side of pan.

Prepare chocolate drizzle by combining 1/2 cup semi-sweet chocolate chips and 2 teaspoons shortening (do NOT use butter , margarine or oil) in small microwave safe bowl. Microwave at HIGH 30 seconds. If not melted, microwave at HIGH for an additional 15 seconds at a time, stirring after each time until chips are melted.

Remove side of pan and drizzle chocolate drizzle over top of cake. Refrigerate 4 to 6 hours. Store covered in refrigerator.

Note: Check any cheesecake for doneness by gently shaking the pan. If it''s set except for a small jiggly area in the center, its''s done.