Preheat the oven to 375°F (190°C). Grease a 9x13-inch baking dish and set aside.
Cook the manicotti pasta according to package instructions. Drain and set aside to cool slightly.
In a large bowl, combine the ricotta cheese, beaten eggs, salt, sugar, pepper, Parmesan cheese, and 2 cups of mozzarella cheese. Stir until smooth and well mixed.
Carefully stuff each cooked manicotti shell with the cheese mixture using a spoon or piping bag.
Spread a thin layer of spaghetti sauce in the bottom of the prepared baking dish. Arrange the stuffed manicotti in the dish and pour the remaining sauce over the top.
Sprinkle the remaining mozzarella cheese over the manicotti.
Cover the dish with foil and bake for 30 minutes. Then, remove the foil and bake for an additional 10 minutes, or until the cheese is bubbly and golden.
Let the manicotti cool for a few minutes before serving. Enjoy your homemade Copycat Olive Garden manicotti!