First melt butter or margarine in a wide, heavy pan. Add chopped or thinly sliced stems and cook, covered, for 3-4 minutes. Stir in chopped leaves and cook 3-4 minutes more. Next sprinkle with 2 tablespoons flour and stir until blended. Gradually blend in chicken broth and milk. Cook and stir until slightly thickened. (If you prefer a smooth green soup, whirl mixture in a blender until it has the consistency desired.) Season to taste with salt and pepper. Makes 4-6 servings. Vocational Dept.