Preheat your oven to 375°F (190°C) and lightly grease your baking dish.

In a large skillet, heat olive oil over medium heat, add onion and garlic, sauté until translucent (about 5 minutes).

Crumble in the ground beef and cook until browned (8–10 minutes), drain excess fat.

Stir in the marinara sauce, let it simmer on low for about 10 minutes.

In a medium bowl, combine ricotta cheese, egg, chopped parsley, and salt and pepper, mix until smooth.

In the prepared baking dish, layer a thin layer of meat sauce, 3 noodles, 1/3 of the ricotta mixture, 1/3 of the mozzarella, and more meat sauce. Repeat twice.

For the final layer, spread remaining meat sauce, top with shredded mozzarella and grated Parmesan.

Cover with foil and bake for 25 minutes, remove foil and bake for an additional 20 minutes until bubbly and golden brown.

Let the lasagna rest for 10-15 minutes before serving.