Boil Pasta Shells: Bring a large pot of salted water to a boil. Add your jumbo pasta shells and cook them for 8–10 minutes, or until al dente. Drain and set aside to cool.

Mix the Filling: In a bowl, combine ricotta cheese, shredded mozzarella, grated Parmesan, large egg, salt, and pepper. Stir until creamy and well combined.

Sauté Spinach: Heat olive oil in a skillet over medium heat. Add minced garlic and sauté until golden brown. Toss in the spinach until wilted, then drain excess moisture before adding to the filling mix.

Assemble the Dish: Preheat your oven to 375°F (190°C). Spread marinara sauce on the bottom of a baking dish. Fill each shell with the spinach-ricotta mixture and place in the dish. Cover with remaining marinara sauce and sprinkle with leftover mozzarella.

Bake: Cover the dish with foil and bake for 20 minutes. Remove the foil and continue to bake for an additional 10 minutes, until cheese is bubbly and golden brown.

Garnish and Serve: Allow the dish to cool for a few minutes. Garnish with fresh basil before serving, and enjoy every comforting bite!