Bring a large pot of salted water to a boil and cook the jumbo pasta shells until al dente. Drain and rinse with cold water.

In a skillet, heat olive oil and sauté garlic for 30 seconds. Add spinach and cook until wilted. Let cool.

In a bowl, combine ricotta, half the mozzarella and Parmesan, spinach, egg, salt, and pepper. Mix well.

Fill each pasta shell with the cheese mixture.

Spread 1 cup marinara sauce on the bottom of a baking dish. Arrange the stuffed shells on top.

Pour the remaining sauce over the shells. Sprinkle with remaining mozzarella and Parmesan.

Cover with foil and bake at 375°F for 25 minutes. Remove foil and bake another 10 minutes until bubbly and golden.

Serve hot, garnished with fresh basil or extra Parmesan.