In a large pot, bring salted water to a rolling boil. Add the lasagna noodles and cook according to package directions until just al dente, usually around 8-10 minutes. Once cooked, drain and lay them flat on a clean kitchen towel or greased baking sheet to prevent sticking.
In a large skillet, heat a generous drizzle of olive oil over medium heat. Add the chopped onion and minced garlic, stirring frequently until the onions are translucent and fragrant, about 3-4 minutes. Incorporate the ground beef and Italian sausage, breaking it up with a spoon. Cook until browned and fully cooked through (approximately 6-8 minutes). Carefully drain any excess fat from the skillet.
Mix in the crushed tomatoes along with the oregano, basil, salt, and pepper. Increase the heat slightly and bring the mixture to a simmer. Let the sauce cook for about 10 minutes, stirring occasionally to blend the flavors.
In a medium bowl, whisk together the ricotta cheese with the egg, half of the grated Parmesan cheese, and a pinch of salt and pepper until the mixture is creamy and well combined.
In a 9x13 inch baking dish, spread a thin layer of the meat sauce on the bottom to prevent sticking. Place three lasagna noodles over the sauce. Follow with one-third of the ricotta mixture, spreading it evenly over the noodles. Top this with one-third of the meat sauce and a handful of shredded mozzarella cheese. Repeat this layering process two more times, and finish with a final layer of meat sauce topped with the remaining mozzarella and Parmesan cheese.
Cover the baking dish tightly with aluminum foil to retain moisture and place it in the preheated oven. Bake for 25 minutes, then carefully remove the foil and continue baking for an additional 15 minutes, or until the cheese is bubbly and lightly browned.
Remove the lasagna from the oven and let it rest for 10-15 minutes before slicing; this helps the layers set and makes serving easier. For an extra pop of flavor, garnish with fresh basil leaves before serving.
Notes
Serve each slice on warm plates, garnished with fresh basil and Parmesan cheese.