Preheat your oven to 375°F (190°C). Get ready to create a deliciously creamy dish!
In a large pot, bring water to a rolling boil. Once boiling, generously add salt and cook the jumbo pasta shells according to the package instructions until they are al dente, usually about 8-10 minutes. Once cooked, drain the pasta and let it cool for a few minutes.
While the shells are cooling, prepare the filling. In a spacious mixing bowl, combine the ricotta cheese, chopped spinach, half of the shredded mozzarella, grated Parmesan cheese, the beaten egg, minced garlic, dried oregano, dried basil, and a sprinkle of sea salt and black pepper. Mix everything together until the ingredients are fully blended and creamy.
Carefully stuff each cooked pasta shell with a generous spoonful of the ricotta-spinach mixture, ensuring they are well-packed but not overstuffed.
In a 9x13 inch baking dish, spread a thin layer of marinara sauce evenly across the bottom.
Arrange the stuffed shells in a single layer on top of the marinara sauce, ensuring the seam side is facing up.
Pour the remaining marinara sauce over the top of the shells, ensuring they are well covered. Finally, sprinkle the rest of the mozzarella cheese over everything.
Cover the baking dish tightly with aluminum foil and place it in the preheated oven. Bake for 25 minutes.
After 25 minutes, carefully remove the foil and continue baking for an additional 10 minutes.
Once done, take the dish out of the oven and let it rest for about 5 minutes before serving. Garnish with fresh basil leaves for a touch of color and flavor!