Combine first 4 ingredients, mixing well. Press into bottom and up sides of a 9 inch springform pan; set aside. Beat cream cheese with electric mixer until light and fluffy. Gradually add 1 c. Sugar and flour, mixing well. Add eggs, one at a time, beating well after each addition. Stir in 2 tablespoons butter and 1 tablespoon Grand Marnier. Spoon into prepared pan and bake at 375 for 30 minutes. Let cool to room termperature on a wire rack; refrigerate 12 hours. Remove sides of pan; garnish with mandarin oranges. Yield: 10 to 12 servings.