Preheat your oven to 375°F (190°C).

In a large pot, bring salted water to a boil and cook the lasagna noodles according to package instructions, about 8-10 minutes, then drain and set aside.

In a large skillet over medium heat, heat olive oil and sauté chopped onion for 3-4 minutes until translucent.

Add ground beef to the skillet, season with salt and pepper, and cook for 6-8 minutes until browned. Add minced garlic and stir for 30 seconds.

Pour in marinara sauce, dried Italian seasoning, and parsley; let simmer for 10-15 minutes.

In a bowl, whisk an egg and mix with ricotta cheese until smooth.

In a baking dish, layer meat sauce, noodles, ricotta, mozzarella, and parmesan; repeat until all ingredients are used, finishing with sauce and cheese on top.

Cover with foil and bake for 35 minutes, then remove foil and bake for another 10-15 minutes until golden.

Let the lasagna rest for 10 minutes before slicing and serving.