In a large skillet over medium heat, sauté one finely chopped onion and minced garlic until translucent, about 3-4 minutes. Add one pound of ground beef, seasoning with salt and pepper, and cook until browned. Stir in 28 ounces of crushed tomatoes and a teaspoon of Italian seasoning. Let the meat sauce simmer for 20 minutes.

In a mixing bowl, combine 15 ounces of ricotta cheese, one cup of shredded mozzarella, and half a cup of grated Parmesan cheese. Season with salt and pepper to taste and mix until smooth.

Gently fill each manicotti shell with the cheese mixture. Arrange the stuffed shells in a greased 9x13-inch baking dish. Pour the meat sauce over the top.

Cover the baking dish with aluminum foil and preheat your oven to 375°F (190°C). Bake for 30 minutes. Remove the foil and bake uncovered for an additional 15 minutes.

Let the dish cool for about 10 minutes before serving, garnished with fresh herbs if desired.