Beat ricotta until smooth, gradually adding 1 1/2 cups sugar and egg yolks. Add anisette, creme de cocoa, flour, vanilla, orange and lemon rind. Beat egg whites with 1/2 cup sugar. Fold whipped cream, egg whites and chocolate bits into the ricotta mixture. Turn into a 12" spring form pan which has been buttered and sprinkled with graham cracker crumbs. Bake in preheated oven 425 degrees for 10 minutes. Lower temperature to 350 degrees and bake 1 hour. Turn off heat and allow to cool in oven with door closed. Refrigerate.