01 -
Cook the jumbo pasta shells in salted water according to the package instructions until al dente, about 8–10 minutes. Drain and set aside to cool slightly.
02 -
In a large bowl, mix ricotta cheese, 1/2 cup shredded mozzarella, Parmesan cheese, and the egg until well combined. Heat olive oil in a skillet over medium heat, sauté garlic for 30 seconds, then add spinach and cook until wilted (2–3 minutes). Combine with the ricotta mixture and season with Italian seasoning, salt, and pepper.
03 -
Preheat the oven to 375°F (190°C). Spread 1 cup marinara sauce evenly across the bottom of a 9×13-inch baking dish. Fill each cooked shell with about 2 tablespoons of ricotta-spinach mixture and place them in the dish, open side up. Cover with remaining marinara sauce. Cover with foil and bake for 20 minutes, then uncover and bake for an additional 10 minutes.
04 -
Allow the dish to rest for a few minutes before serving to meld the flavors. Garnish with fresh basil leaves if desired.