enough sauce to cover the bottom of a 15 x 10-inch ovenproof dish. Add some squash in a single layer, then add a generous layer of sauce. Add about one-third of the egg and spread it around the dish. Repeat the squash-sauce-egg sequence layering one or two more times depending on how much you have left, finishing with a light layer of sauce. Bake for 25 to 30 minutes, until a knife easily pierces the squash.
