Vegetarian Baked Ziti

Position rack in lower third of oven; preheat to 450°F. Coat a 9-by-13-inch baking dish with cooking spray.

Toss cauliflower, zucchini, bell pepper, oil and oregano together in a large bowl. Sprinkle with 1/4 teaspoon each salt and pepper; toss again to mix. Spread the mixture in an even layer on a large rimmed baking sheet. Roast the vegetables until slightly charred and tender, about 20 minutes. Remove from the oven and set aside. Do not turn the oven off.

Meanwhile, bring a large pot of water to a boil over medium-high heat. Add ziti and cook according to package directions. Drain the ziti and transfer to a large heatproof bowl. 

Add the roasted vegetables, marinara and the remaining 1/2 teaspoon salt and 1/4 teaspoon pepper to the ziti in the bowl. Toss well to coat. Spread the mixture evenly in the prepared baking dish.

Stir ricotta, Parmesan and parsley together in a small bowl. Add spoonfuls of the ricotta mixture to the pasta mixture in the baking dish and gently stir to loosely combine. Sprinkle the mixture evenly with mozzarella. Bake at 450°F until the casserole is bubbly and the cheese is melted and slightly browned, about 25 minutes. Let stand for 5 minutes before serving.