Combine crumbs and 2 tablespoons of the margarine; set aside. Add onion to remaining margarine. Sauté over low heat. Add flour, salt and pepper. Stir in milk. Increase heat to medium; cook until bubbly and thickened, stirring constantly. Add cheese; stir until smooth. Stir in carrots and parsley flakes. Spread in shallow 1 ½-quart baking dish. Sprinkle with crumb mixture. Bake in 350° oven about 20 minutes, or until bubbly and crumbs are golden brown.