Place crumbs in mixing bowl and add 1/4 cup sugar and cinnamon, then stir in 1/3 cup butter. More butter, up to 3/4 cup, may be added if needed. Butter an 8-inch springform pan on bottom and sides. Sprinkle thin layer of crumbs on bottom of pan and press down with metal 1/4-cup measure. Pat crumbs on sides and press into position with side of measuring cup. Work around sides with fingers to make crumbs of even height. Any remaining crumbs may be added to bottom crust. Bake crust at 350F 5 minutes. To make filling, beat eggs until light, then add 1/2 cup sugar and beat 5 minutes. Add cream cheese and 1 teaspoon each vanilla and Grand Marnier and mix well. Turn into Crumb Crust and bake at 375F 20 minutes. Cool 15 minutes. To make topping, blend sour cream, 6 tablespoons sugar and 1 teaspoon each vanilla and Grand Marnier well, then pour over filling and bake at 475F 5 minutes. Cool cake then chill overnight before serving.