12 lasagna noodles
1 tablespoon vegetable oil
2 cloves garlic, minced
1 onion, diced
2 cups ricotta cheese
2-1/2 cups shredded mozzarella, divided
1/2 cup grated Parmesan cheese, divided
1 teaspoon dried oregano
1/2 teaspoon salt
1/4 teaspoon pepper
1 (10-ounce) package frozen chopped spinach, thawed and squeezed dry
1 (32-ounce) jar pasta sauce
Cook the lasagna noodles in boiling, salted water just until tender. Drain in a colander.
While the pasta cooks, heat the oil in a large skillet over medium-high heat. Add the garlic and onion and cook, stirring, until the onion is soft and translucent, about 5 minutes. Remove from the heat and let cool.
Preheat the oven to 350 degrees F.
In a large mixing bowl, combine the ricotta, 2 cups of the mozzarella, and 1/4 cup of the Parmesan cheese with the oregano, salt, pepper and spinach and mix together. Stir in the onion and garlic.
Spread about 1/2 cup of pasta sauce in the bottom of a 13-by-9-inch baking dish.
To form the rolls, lay a noodle out flat and top it with about 1/3 cup of the cheese mixture, spreading it over the noodle so it covers all but 1/2 inch at each end. Roll the noodle up and place it, seam side down, in the baking dish.
Repeat with the remaining noodles and filling.
Pour the remaining sauce over the rolls and sprinkle with the remaining mozzarella and Parmesan cheese. Cover with aluminum foil.
Bake, covered, in the preheated oven for 30 minutes. Remove the foil and continue to cook uncovered for 5 to 10 minutes longer, until the cheese on top is browned and bubbling.
Serve hot.