Preheat your oven to 375°F (190°C) and gather a 9x13-inch baking dish.

In a large pot of boiling salted water, cook the manicotti for about 6 minutes until al dente.

In a large skillet, heat olive oil over medium heat and sauté the diced onion until translucent.

Add garlic and ground beef; cook until the meat is no longer pink. Stir in crushed tomatoes and season with salt and pepper. Let simmer for 10 minutes.

In a mixing bowl, combine ricotta cheese, mozzarella, Parmesan, egg, garlic powder, and Italian seasoning. Mix well.

Stuff each manicotti tube with the cheese mixture using a small spoon or piping bag. Place them in the prepared baking dish standing upright.

Pour the meat sauce evenly over the stuffed manicotti and sprinkle with more shredded mozzarella.

Cover with aluminum foil and bake for 25 minutes. Remove foil and bake for an additional 10-15 minutes until the cheese is bubbling and lightly golden.

Let the dish sit for 5-10 minutes before serving. Garnish with fresh basil or extra Parmesan, then slice and serve.