1 lb. ziti pasta
1 tbsp. extra-virgin olive oil
1 medium onion, chopped
2 cloves garlic, minced
2 tbsp. tomato paste
1 tsp. dried or fresh oregano
1 (28-oz.) can crushed tomatoes
1 1/2 c. fresh ricotta
1 (10-oz). package frozen spinach, drained and chopped
Zest of 1/2 lemon
1/2 tsp. crushed red pepper flakes
Freshly ground black pepper
2 tbsp. thinly sliced basil, plus more for garnish
1/2 c. grated Parmesan
2 c. shredded mozzarella
- Preheat oven to 350°. In a large pot of boiling salted water, cook pasta until very al dante; drain.
- In a large saucepan over medium heat, heat oil. Add onion and cook, stirring often, until onion is soft, about 5 minutes minutes.
- Stir in garlic, tomato paste, and oregano and cook 2 minutes more, until slightly darkened. Add crushed tomatoes and season with salt and pepper. Bring sauce to a simmer, reduce heat and cook, stirring occasionally, until slightly reduced and flavors have melded, 15 to 20 minutes. Remove from heat and stir in basil.
- While sauce is reducing, stir to combine ricotta, spinach, lemon zest, and crushed red pepper flakes in a medium bowl.
- In a large bowl, combine sauce and pasta. Fold in ricotta mixture, leaving large clumps. Spread about half of the pasta mixture into the bottom of a large casserole dish. Sprinkle half of the mozzarella and Parmesan over the pasta. Top with the rest of the pasta mixture and sprinkle with the remaining cheeses.
- Cover with foil and bake until cheese is bubbling, about 20 to 25 minutes. Garnish with more basil before serving.