1. Bring a large pot of salted water to a boil and cook the jumbo pasta shells until al dente (about 9 minutes). Drain and rinse with cold water. Lay them on a baking sheet to prevent sticking.

2. In a large bowl, combine ricotta, spinach, 1/2 cup mozzarella, Parmesan, egg, garlic, Italian seasoning, salt, and pepper. Mix until well combined.

3. Preheat oven to 375°F (190°C).

4. Spread 1 cup of marinara sauce on the bottom of a 9×13-inch baking dish.

5. Fill each pasta shell with the ricotta-spinach mixture using a spoon or piping bag.

6. Arrange filled shells in the baking dish over the marinara layer.

7. Spoon the remaining 1 cup marinara sauce over the shells. Top with the remaining 1/2 cup mozzarella.

8. Cover with aluminum foil and bake for 25 minutes. Remove foil and bake an additional 10 minutes until cheese is melted and slightly golden.

9. Let rest for 5–10 minutes before serving. Garnish with fresh herbs or more Parmesan, if desired.