Bring a large pot of salted water to a boil, then cook manicotti shells until al dente, about 7-9 minutes. Drain and place them on a towel to cool, preventing them from sticking together.

In a spacious skillet, heat 2 tablespoons of olive oil over medium heat. Sauté minced garlic until fragrant, about 1 minute. Add fresh spinach and cook for approximately 3 minutes, stirring until just wilted, then remove from heat.

In a mixing bowl, combine the creamy ricotta, sautéed spinach, grated Parmesan, and the egg. Stir well until the mixture is smooth and uniform in consistency.

Carefully spoon the delightful spinach-ricotta mixture into each cooled manicotti shell. Arrange the filled shells side by side in a greased baking dish.

Pour marinara sauce over the stuffed shells, ensuring each one is well-covered. Sprinkle extra Parmesan cheese on top for that irresistible cheesy goodness!

Preheat your oven to 375°F (190°C). Cover the baking dish with foil and bake for 25 minutes. Remove the foil and continue baking for an additional 10 minutes, or until the top is bubbly and golden.