Mix graham cracker crumbs with 2 tablespoons sugar, cocoa and cinnamon. Gradually add melted butter, stirring until crumbs are evenly coated. Press evenly into bottom and two-thirds up sides of buttered 23 cm springform pan that has been covered outside with aluminum foil. Refrigerate until ready to fill. Melt chocolate in double boiler; remove from heat. Place cream cheese in bowl, beat on medium speed until smooth and fluffy, about 10 minutes. Beat in sour cream, 0.75 cup sugar and orange oil. Add eggs, one at a time beating in between. Beat for 1-2 minutes more. Using rubber spatula, gently stir in chocolate until blended. Stir slowly 1-2 minutes to dispel bubbles. Pour batter into prepared pan. Bake in 350 degree oven until puffed and no longer shiny, 35-40 minutes. Center will look wet but will firm up when chilled. Transfer to wrie rack to cool. When cool, remove foil and sides of pan. Cover and refrigerate until firm enough to cut easily, 4-5 hours or overnight. Sift cocoa generously over cake before serving. Serves 6-8. From Simple American Cooking, Williams-Sonoma A Catalog for Cooks, Christmas 1994 ----