Pour melted butter in a 9-inch pie pan and put zucchini and onion in, stirring to coat them well with the butter.
In a small bowl, mix the warmed half-and-half, 1/2 cup cheese, egg, salt and pepper together and pour over the zucchini. Top with the bread crumbs. Bake about 30 minutes, uncovered.
Sprinkle the remaining 1/4 cup cheese over the bread crumbs and bake several more minutes, until the cheese is melted and the top is nice and crusty. You can also melt the cheese in a broiler for a few minutes.
Thrifty tip: Make your own bread crumbs for this recipe; it's a lot cheaper than buying them. Take 2 slices of day-old bread (or even leftover toast) and process them in a food processor or, if they are very dry, crush them with a rolling pin.
Nutrition information per serving:
Calories303Fat20 gSodium583 mg