These Spinach and Ricotta Stuffed Shells are the ultimate Italian-American comfort food — jumbo pasta shells packed with a creamy, seasoned three-cheese and spinach filling, nestled in rich marinara sauce, and baked until the mozzarella on top is golden and bubbling. They're surprisingly easy to make, naturally vegetarian, perfect for feeding a crowd, and taste even better the next day as leftovers.
Preheat your oven to 375°F (190°C). Lightly grease a 9x13 inch baking dish with olive oil, then spread 1 cup of marinara sauce evenly across the bottom and set aside.
Bring a large pot of well-salted water to a rolling boil, then cook the jumbo shells for 2 minutes less than the package directions (about 9 to 10 minutes). Drain, rinse with cool water, and lay flat on a clean towel to prevent sticking.
Heat 2 tablespoons of olive oil in a large skillet over medium heat, add the minced garlic, and stir for 30 to 45 seconds until fragrant. Add the fresh spinach and toss for 2 to 3 minutes until fully wilted, then remove from heat, cool slightly, and roughly chop.
In a large bowl, combine the ricotta, 1 cup mozzarella, ¼ cup Parmesan, the egg, Italian seasoning, garlic powder, red pepper flakes, salt, pepper, and the chopped spinach. Stir until well combined and taste to adjust seasoning.
Spoon 2 to 3 tablespoons of the ricotta filling into each shell and arrange them open-side up in a single layer over the marinara-coated baking dish.
Pour the remaining 2 cups of marinara sauce evenly over the shells, then sprinkle the reserved ½ cup mozzarella and ¼ cup Parmesan across the top.
Cover the dish tightly with foil and bake at 375°F for 25 minutes.
Remove the foil and bake for an additional 10 to 15 minutes until the cheese is bubbly and golden. Rest for 5 to 10 minutes before serving, then garnish with fresh basil if desired.
Notes
Undercook the shells by 2 minutes — they finish cooking in the oven. Overcooked shells become soggy and difficult to fill.
If using frozen spinach, use 10 oz and squeeze out every drop of moisture with a clean kitchen towel before chopping. Excess water will make the filling runny.
Whole milk ricotta produces a noticeably creamier filling than part-skim. Use it if you can find it.
Always spread sauce on the bottom of the baking dish before adding the shells — this prevents sticking and burning.
Make ahead: assemble fully, cover with foil, and refrigerate up to 24 hours. Bake as directed, adding 5 to 10 extra minutes since the dish will be cold.
Freeze before baking: wrap tightly in plastic wrap and foil and freeze up to 3 months. Thaw overnight in the fridge before baking.
For a meat version, brown ½ lb Italian sausage or ground beef before adding the garlic, drain excess fat, and mix the cooked meat into the ricotta filling.
For a white sauce version, swap the marinara for a creamy bechamel sauce for a richer Florentine-style result.
Reheat leftovers in a 350°F oven, covered with foil, for 20 to 25 minutes. Spoon a little extra sauce over the shells first to keep them from drying out.
Leftovers keep well in the fridge for up to 4 days and often taste better the next day after the flavors have had time to meld.