For the Rich Marinara Sauce:

• 1 (28-ounce) can crushed tomatoes – The base for our flavorful sauce.
• ½ teaspoon dried oregano – Adds an authentic Italian aromatic note.
• ½ teaspoon dried basil – A classic pairing with tomatoes for a sweet, peppery flavor.
• ¼ teaspoon salt – To enhance all the flavors.
• ¼ teaspoon pepper – A touch of warmth and spice.
• 1 teaspoon sugar – Helps balance the acidity of the tomatoes.

For the Pasta Shells:

• 24 large jumbo pasta shells, about 3/4 of a 12-ounce box. Look for large, sturdy shells that can hold ample filling.

For the Creamy Spinach & Cheese Filling:

• 2 cups cottage cheese – Contributes a lighter texture and tangy flavor.
• 15 ounces (about 2 cups) part-skim ricotta cheese – For that classic creamy, rich Italian-American filling.
• ½ teaspoon salt – Essential for seasoning the filling.
• ¼ teaspoon pepper – A touch of spice to round out the flavors.
• ½ teaspoon dried parsley – Adds herbaceous freshness to the filling.
• ½ teaspoon dried oregano – Another layer of classic Italian seasoning.
• ½ teaspoon dried basil – Complements the other herbs beautifully.
• 10 ounces frozen chopped spinach, thawed and squeezed dry of excess liquid – The key to adding vibrant color and nutrients without extra moisture.
• ½ cup freshly grated Parmesan cheese – For sharp, salty depth of flavor.
• 1 ½ cups shredded mozzarella cheese – For that essential gooey, melty texture.

• Prepare the Sauce: In a medium saucepan, combine the crushed tomatoes, dried oregano, dried basil, salt, pepper, and sugar. Stir everything together thoroughly. Bring the sauce to a gentle simmer over medium heat. Once simmering, reduce the heat to low and let it continue to cook for 10-15 minutes, allowing the flavors to meld and deepen. Remove from heat and set aside.
• Cook the Pasta Shells: While your sauce is simmering, bring a large pot of heavily salted water to a rolling boil. Add the jumbo pasta shells and cook them al dente according to the package directions. It’s crucial not to overcook them, as they will continue to bake later. Al dente shells will be firm but pliable enough to stuff. Drain the cooked shells immediately and arrange them in a single layer on paper towels or parchment paper to prevent them from sticking together. This also helps them cool slightly and makes them easier to handle.
• Mix the Filling: In a medium-sized mixing bowl, combine the cottage cheese, ricotta cheese, salt, pepper, dried parsley, dried oregano, and dried basil. Stir until all ingredients are well-incorporated and the mixture is smooth. Add the thawed and thoroughly squeezed-dry chopped spinach to the cheese mixture. Mix until the spinach is evenly distributed. Finally, stir in the freshly grated Parmesan cheese and shredded mozzarella cheese, ensuring they are well combined.
• Prepare for Baking: Lightly grease a 9×13-inch baking pan with cooking spray or a little olive oil. Preheat your oven to 350 degrees F (175 degrees C).
• Assemble the Shells: Spoon approximately half of the prepared tomato sauce onto the bottom of your greased baking pan, spreading it evenly to create a bed for the shells. Carefully fill each cooked pasta shell with an even amount of the creamy cheese and spinach filling. Aim for about 1/4 cup of filling per shell, adjusting as needed. Arrange the filled shells seam-side up on top of the sauce in the pan, typically forming three neat rows of eight shells.
• Bake to Perfection: Pour the remaining sauce evenly over the top of the stuffed shells, ensuring they are well covered. If desired, sprinkle an additional layer of shredded mozzarella or Parmesan cheese over the top for an extra cheesy crust. Cover the baking dish tightly with aluminum foil. Bake in the preheated oven for 35-40 minutes, or until the sauce is bubbly and the shells are heated through. Remove the foil and bake for another 5-10 minutes, or until the cheese on top is golden brown and melted. Take the pan from the oven and let the shells rest for 5-10 minutes before serving. This allows the dish to set and makes for easier serving.

Spinach Preparation is Key: The most crucial step when using frozen spinach is to thoroughly thaw it and squeeze out as much excess liquid as possible. Use a clean kitchen towel or paper towels to really wring it dry. This prevents the filling from becoming watery and ensures your shells have the perfect creamy consistency. Allowing the finished dish to sit for a few minutes after baking also helps absorb any remaining moisture.

Cheese Layer Customization: For those who love an extra cheesy topping, feel free to reserve some of the mozzarella or Parmesan cheese (or shred an extra half cup) to sprinkle over the sauce-covered shells before baking. This creates a beautiful, golden-brown, bubbly cheese crust that’s utterly irresistible.

Freezer Meal Instructions: This recipe is truly fantastic as a freezer meal. To prepare for freezing, fully assemble the shells in the baking dish, cover them completely with sauce, and then top with a double layer of aluminum foil. Freeze the uncooked dish. When you’re ready to bake, you can cook it directly from frozen. Simply add about an hour to the total baking time, keeping it covered for roughly 1 to 1.5 hours, then remove the foil and bake uncovered for an additional 15-30 minutes, or until heated through and bubbling. Make sure the internal temperature reaches a safe level (around 165°F or 74°C).

Meat Lover’s Variation: For a heartier, non-vegetarian version, consider browning a half pound of ground beef or Italian sausage and mixing it into the tomato sauce before simmering. This adds a delicious layer of flavor and protein.