* I've just recently found Oreo Cookie crumbs in a box. A great time saver for the lazy. Heat oven to 160ºC . Mix crumbs, cinnamon, and butter. Press onto bottom of 23 cm springform pan. Bake 10 minutes. Increase oven temperature to 180ºC . 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 160ºC . 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 :