In a large skillet or pot, cook the ground beef and Italian sausage over medium heat until browned, breaking it up with a spatula. Drain off excess fat.

Add the chopped onion and minced garlic, sautéing for 2-3 minutes until softened.

Stir in the crushed tomatoes, tomato sauce, tomato paste, beef broth, sugar, basil, oregano, and optional red pepper flakes. Season with salt and pepper to taste.

Let the sauce simmer uncovered on low heat for 20-30 minutes, stirring occasionally, until it thickens slightly.

In a mixing bowl, combine the ricotta cheese, egg, Parmesan cheese, parsley, salt, and black pepper. Mix until smooth and well-blended.

Bring a large pot of salted water to a boil and cook the lasagna noodles according to the package instructions. Once cooked, drain and lay them flat on a baking sheet to prevent sticking.

Preheat your oven to 375°F (190°C).

In a 9x13 inch baking dish, spread a thin layer of meat sauce on the bottom.

Place a layer of cooked lasagna noodles on top, followed by a layer of the ricotta mixture.

Spread another layer of meat sauce over the ricotta, then sprinkle with a layer of shredded mozzarella cheese.

Repeat until you’ve used all the ingredients, finishing with a generous topping of meat sauce and mozzarella cheese.

Sprinkle the top with additional grated Parmesan cheese.

Cover the lasagna with aluminum foil and bake in the preheated oven for 25 minutes.

After 25 minutes, remove the foil and bake for another 20-25 minutes until the cheese is bubbly and golden brown.

Let the lasagna rest for 10-15 minutes before slicing and serving to help the layers set.