Boil the eggs half an hour. Drop them into cold water; shell and quarter them and lay them in a buttered baking dish. Make a white sauce of the hot milk with butter, and flour enough to thicken. Season and stir until smooth. Chop the onions, add to the sauce and pour over the eggs, sprinkle the top with cracker crumbs, dots of butter and the grated cheese. Bake until a nice brown and serve immediately.