Cook Pasta: Boil shells in salted water until al dente. Drain and cool.
Sauté Greens: Heat olive oil in a pan, sauté garlic, then wilt spinach. Let cool.
Mix Filling: Combine ricotta, Parmesan, egg, seasoning, and cooled spinach mixture.
Stuff: Fill each shell with the cheese mixture.
Assemble: Spread 1 cup of sauce in a baking dish. Place shells on top. Pour remaining sauce around them. Top with mozzarella.
Bake: Cover with foil. Bake at 180°C (350°F) for 20 mins. Uncover and bake 10–15 mins more until golden.