Peel, slice and steam the carrots until tender. Mash. Saute the green pepper and onion in the 4 tablespoons butter or margarine. Stir in the flour, milk, salt and sugar. Cook until thickened. Add the mashed carrots and put in a greased casserole.
Melt the 1 tablespoon butter or margarine and in this toss the crumbs until golden. Spread over the carrots. Bake at 350 degrees F for 30 minutes.