Bring a large pot of salted water to a boil. Add the lasagna noodles and cook according to package instructions until al dente. Drain and set aside.
In a large skillet, heat the olive oil over medium heat. Add the diced onion and minced garlic. Sauté until the onion is translucent, about 3-4 minutes.
Add the ground beef and Italian sausage to the skillet. Cook until browned, breaking it up into smaller pieces with a spoon. Drain excess fat if necessary.
Stir in the crushed tomatoes, oregano, salt, and pepper. Simmer for about 10-15 minutes, allowing the flavors to meld. Remove from heat.
In a bowl, mix the ricotta cheese, egg, basil, parsley, and ¼ cup of Parmesan cheese until well combined. Add a pinch of salt and pepper.
In a 9x13 inch baking dish, spread a layer of the meat sauce on the bottom. Place 4 lasagna noodles on top, followed by half of the ricotta mixture, a third of the mozzarella cheese, and another layer of meat sauce. Repeat the layers, finishing with a final layer of meat sauce, mozzarella cheese, and the remaining Parmesan on top.
Cover the dish with aluminum foil and bake in the preheated oven for 25 minutes. Remove the foil and bake for an additional 15 minutes until the cheese is bubbly and golden.
Let the lasagna cool for about 10-15 minutes before cutting into squares and serving.
Notes
Let the lasagna cool before serving for easier slicing.