Preheat oven to 325. Mix crumbs, cinnamon, and butter. Press onto the bottom of a 9-inch springform pan and bake 10 minutes. Increase oven temperature to 350. Beat cream cheese and sugar at medium speed 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. Melt chocolate in double boiler and add it to one part. Blend Gran Marnier and orange peel into remaining part. Pour chocolate batter over crust and bake 30 minutes. Reduce oven temperature to 325. Carefully spoon orange batter over chocolate layer. Continue baking another 40 minutes. Turn off oven and prop open oven door. Remove cheesecake when oven has cooled. Loosen cake from rim of pan. Recipe By :