Melt the butter and add flour. When blended together and bubbling, add the milk gradually, stirring constantly. Cook until the sauce is smooth and thickened. Season with 1/2 teaspoon salt and 1/8 teaspoon pepper. Separate the eggs, mix the yolks, 1/4 cup of sauce, 1/4 teaspoon salt and 1/8 teaspoon pepper and beat until thick. Beat egg whites until stiff and fold into egg yolks. Grease sides and bottom of omelet pan. Pour in mixture and cook until lightly browned. Bake at 300ºF. until omelet is cooked. Remove to a platter. Garnish with asparagus and pour remaining white sauce around omelet.