Giant Stuffed Shells Florentine My Familys Favorite

Ingredients

• 1 tablespoon olive oil (15 ml)
• 1 medium onion, chopped (approx. 1 cup) (150g)
• 2 cloves garlic, minced
• 1 (28 ounce) can crushed tomatoes (794g)
• 1 (15 ounce) can tomato sauce (425g)
• 1 teaspoon dried oregano
• ½ teaspoon dried basil
• ¼ teaspoon red pepper flakes (optional)
• Salt and freshly ground black pepper to taste
• 1 (12 ounce) box jumbo pasta shells (about 340g)
• Salt for pasta water
• 15 ounces ricotta cheese (425g), whole milk or part-skim
• 10 ounces frozen spinach, thawed and squeezed dry (283g)
• 1 large egg, lightly beaten
• ½ cup grated Parmesan cheese (50g), plus more for topping
• ¼ cup chopped fresh parsley
• ¼ teaspoon ground nutmeg
• 1 cup shredded mozzarella cheese (100g)