Preheat oven to 375°F; grease a 9x13-inch dish.
Mix squeezed-dry spinach, ricotta, eggs, salt, pepper, nutmeg, garlic, and 1/2 cup Parmesan well in a large bowl.
Spread 1 cup marinara in prepared dish's bottom.
Layer 4 noodles, half the spinach-ricotta mixture, one-third of remaining marinara, and one-quarter of mozzarella.
Repeat with noodles, remaining spinach mixture, more sauce, and another quarter mozzarella.
Top with remaining noodles, marinara, mozzarella, and Parmesan.
Cover with foil; bake 45 minutes. Uncover; bake another 15 minutes, until cheese is bubbly and lightly browned.
Sprinkle with basil; stand 15 minutes before serving.