* I've just recently found Oreo Cookie crumbs in a box. A great time saver for the lazy. Heat oven to 325 F. Mix crumbs, cinnamon, and butter. Press onto bottom of 9-inch springform pan. Bake 10 minutes. Increase oven temperature to 350 F. Beat cream cheese and sugar at medium speed with electric mixer until well blended. Add eggs, one at a time, beating well after each addition. Blend in sour cream and vanilla. Separate batter into 2 equal parts. Blend chocolate into one part. Blend liqueur and peel into remaining part. Pour chocolate batter over crust. Bake 30 minutes. Reduce oven temperatue to 325 F. Spoon remaining batter over chocolate layer. Continue baking another 30 minutes. Turn off oven and prop open oven door; remove cheesecake when oven has cooled. Loosen cake from rim of pan. I think cheesecake in general is best when chilled over night, but it is not necessary. Recipe By :