Preheat oven to 425 degrees Fahrenheit (220 degrees Celsius). Place vegetables in a large bowl and drizzle with olive oil. Season with salt and pepper and toss to coat.

Spray a baking sheet with cooking spray. Spread vegetables in an even layer onto the baking sheet and sprinkle lightly with oregano. Roast for about 40–45 minutes in the center of the oven until edges begin browning slightly.

While vegetables are roasting, prepare the sauce by melting the butter in a medium saucepan. Add garlic and stir gently until lightly browned and fragrant. Add pizza sauce and heavy cream. Season with salt and pepper to taste. Cook until heated through.

Lower oven temperature to 350 degrees Fahrenheit (175 degrees Celsius).

To assemble the lasagna, spread about one third of the sauce onto the bottom of a nine- x 13-inch (20- x 30-centimeter) pan. If you’re using frozen ravioli, make sure to defrost completely before assembling. Using one entire package for the bottom layer, place the ravioli into the sauce, lining them up in even rows, overlapping slightly, taking care to cover the entire pan. Spoon half of the roasted vegetables over the ravioli and sprinkle one cup of spinach leaves on top. Top with half of the shredded cheese and sprinkle with one tablespoon of Parmesan cheese. Repeat with the second package of ravioli and remaining vegetables and spinach. Pour the remaining two thirds of sauce over the spinach leaves and top with both cheeses.

Place pan into the oven and bake covered for about 35–40 minutes, until cheese is fully melted. Uncover and return to the oven. Broil for an additional three to four minutes or until cheese is bubbly and slightly browned. Serve immediately.