Preheat your oven to 375°F (190°C).

In a large pot, bring salted water to a boil. Cook the jumbo pasta shells according to package directions until al dente, about 9-11 minutes.

In a skillet, heat olive oil, add minced garlic and sauté until fragrant, then toss in fresh spinach and cook until wilted.

In a large mixing bowl, combine ricotta, mozzarella, Parmesan, egg, and the sautéed spinach until well mixed. Add nutmeg if desired.

Spread marinara sauce across the bottom of a baking dish and fill each shell with the cheese mixture, placing them seam side up.

Pour remaining marinara sauce over the stuffed shells and sprinkle with more mozzarella.

Cover with foil and bake for 25 minutes. Remove foil and bake for an additional 10 minutes until bubbly and golden.

Let sit for a few minutes, then garnish with basil or parsley and serve warm.