Cook the lasagna noodles according to package instructions, about 8-10 minutes until al dente. Drain and set aside.
In a large pan over medium heat, add ground beef, chopped onion, and minced garlic. Cook for about 5-7 minutes until the meat is browned and onions are translucent.
Pour in marinara sauce, Italian seasoning, and fresh parsley. Let it simmer for about 10-15 minutes until the sauce thickens.
In a medium bowl, mix ricotta cheese, egg, and a dash of salt and pepper until well combined.
Shred mozzarella in a bowl for layering.
In a large baking dish, spread a thin layer of sauce, then layer noodles, ricotta mixture, mozzarella, and Parmesan. Repeat layers until the top.
Cover with foil and bake at 375°F (190°C) for 30 minutes. Remove foil and bake for an additional 30 minutes until golden and bubbly.
Let it sit for at least 15 minutes before serving.
Notes
For a crispier top, consider broiling for 1-2 minutes at the end. Best served with a salad and garlic bread.