Preheat the oven to 375°F (190°C).

Cook the lasagna noodles in salted water according to package instructions. Drain and lay flat to prevent sticking. (If using no-boil noodles, skip this step.)

In a large skillet over medium heat, brown the ground beef and Italian sausage, breaking up the meat. Drain excess fat.

Add the chopped onion and minced garlic to the skillet. Cook until the onion is soft and translucent, about 4–5 minutes.

Stir in the crushed tomatoes, basil, parsley, salt, and pepper. Bring to a simmer and cook gently for 30 minutes to develop flavor.

In a medium bowl, combine ricotta cheese, the egg, and a pinch of salt. Mix until smooth.

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

Lay down a single layer of noodles, spread about one-third of the ricotta mixture over the noodles, and sprinkle with a layer of mozzarella and a little Parmesan.

Repeat layers (sauce → noodles → ricotta → cheeses) two more times, finishing with meat sauce and the remaining mozzarella and Parmesan on top.

Cover the dish tightly with foil and bake for 25 minutes.

Remove the foil and bake another 25 minutes, until the top is bubbly and golden.

Let the lasagna rest for 10 minutes before slicing so the layers set.