Tomato Vegetable Casserole

Tried this and loved it. We don't like zucchini so we used butternut squash instead. Not often you find a genuinely delicious and healthy recipe.
Ingredients
1 medium potato, peeled and cut into 1/2-inch pieces
1 medium yam, peeled and cut into 1/2-inch pieces
1 red bell pepper, seeded and cut into 1/2-inch pieces
2 carrots, peeled and cut into 1/2-inch pieces
5 tablespoons olive oil
1 red onion, thinly sliced into rings
2 small or 1 large zucchini, cut crosswise into 1/4-inch-thick pieces
Salt and pepper
2 large ripe tomatoes, cut crosswise into 1/4-inch thick slices
1/2 cup grated Parmesan
2 tablespoons dried Italian-style bread crumbs
Fresh basil sprigs, for garnish
Directions
Preheat the oven to 400 degrees F.
Toss the potato, yam, bell pepper, carrots, and 2 tablespoons of olive oil in a 13 by 9 by 2-inch baking dish to coat. Sprinkle with salt and pepper and toss until coated. Spread vegetables evenly over the bottom of the pan.
Arrange the onion slices evenly over the vegetable mixture. Arrange the zucchini over the onion. Drizzle with 2 tablespoons of oil. Sprinkle with salt and pepper. Arrange the tomato slices over the zucchini.
Stir the Parmesan and bread crumbs in a small bowl to blend. Sprinkle the Parmesan bread crumbs over the vegetables in the baking dish. Drizzle with the last tablespoon of olive oil.
Bake uncovered until the vegetables are tender, and the topping is golden brown, about 40 minutes. Garnish with fresh basil sprigs, if desired.