Old-School Baked Ziti Loaded with Spinach

2 Tbsp. olive oil

1 medium onion, chopped

2 garlic cloves, minced

1 jar pureed tomatoes

1 teaspoon dried oregano

Red pepper flakes, to taste

1 pound pasta, cooked al dente and drained

3/4 pound mozzarella, coarsely grated

2/3 cup finely grated pecorino or parmesan cheese

1/2 pound spinach, rinsed and cut into thin ribbons

Heat oven to 400 degrees F. Cook pasta until quite al dente, or 2 minutes less than the suggested cooking time. Reserve 1/2 cup cooking water, then drain pasta. Heat a large sauté pan — if yours is ovenproof, you can even use it as your final baking vessel — over medium heat. Coat with 2 Tbsp. of olive oil, and heat oil. Add onion, garlic, oregano, pepper flakes, and salt over medium-high heat for 6 to 8 minutes or until onions are soft and translucent; stirring frequently. Add tomato puree and stir to combine. Reduce heat to medium-low and simmer for 5 minutes. Adjust seasonings to taste. If it’s become quite thick, stir in reserved pasta water. Add spinach and cook until wilted, just another minute. Stir in drained pasta and heat together for one minute. Pour half of pasta mixture into a 9×13-inch baking dish, lasagna pan, or other 3-quart baking vessel. Sprinkle with half of each cheese. Pour remaining pasta and sauce over, and finish with remaining cheese. Bake in heated oven for 30 minutes or until bubbly and brown on top.