Preheat oven to 350. Thinly slice zucchini (1/8 inch).
Spread 1 c sauce in baking dish. Add a layer of overlapping zucchini slices. Add half the ricotta cheese, a third of the shredded cheese, and half the vegetables. Top with 1 c sauce.
Repeat, then sprinkle the last of the cheese on top.
Bake for one hour until bubbly. Let cool, then refrigerate overnight. Cut into pieces, reheat, and serve.