In a large skillet, saute onion and green peppers in the margarine. Using a wooden spoon, stir flour, salt, pepper and milk into the sauteed mixture. Stir corn kernels and egg into the mixture before pouring the entire concoction into an ungreased medium-size casserole dish.
Combine cracker crumbs and melted butter in a small bowl. Pour the mixture over the casserole.
Bake in a preheated 350 degrees F (175 degrees C) oven for 30 to 35 minutes.
