Cook the manicotti shells according to the package instructions. Be careful not to overcook them, as they will continue to cook in the oven. Drain and set aside.
In a large mixing bowl, combine the ricotta cheese, grated Parmesan cheese, shredded mozzarella cheese, beaten eggs, chopped fresh herbs, sautéed garlic, and onion. Mix well until all the ingredients are evenly incorporated.
Preheat your oven to 375°F (190°C).
Spread a thin layer of tomato sauce on the bottom of a baking dish.
Take a manicotti shell and spoon the ricotta mixture into it. Gently press the mixture down using the back of a spoon to ensure it fills the entire shell. Repeat with the remaining manicotti shells.
Arrange the filled manicotti shells in the baking dish, nestling them close together.
Pour the remaining tomato sauce over the manicotti, covering them completely.
Sprinkle shredded mozzarella cheese on top of the sauce, creating a generous layer.
Cover the baking dish with aluminum foil and bake for 25 minutes.
Remove the foil and continue baking for an additional 10-15 minutes, or until the cheese is golden and bubbly.
Once done, remove the baking dish from the oven and let it cool for a few minutes.
Garnish with fresh basil leaves and grated Parmesan cheese before serving.
Serve the manicotti hot and enjoy!