Preheat your oven to 375°F (190°C). Bring a large pot of salted water to a boil, then cook the lasagna noodles according to package instructions (8-10 minutes). Drain and rinse under cold water.

In a medium-sized skillet, heat 2 tablespoons of olive oil over medium heat. Add the chopped onion, sauté until golden (about 5 minutes). Add the ground beef, cook until browned (7-10 minutes). Season with salt, pepper, and minced garlic. Stir in marinara sauce, dried Italian seasoning, and parsley. Let simmer for 10-15 minutes.

In a mixing bowl, combine ricotta cheese with one beaten egg. Stir until well combined.

In a greased 9x13-inch baking dish, layer 1 cup of meat sauce, noodles, half of the ricotta mixture, and a layer of mozzarella. Repeat layers, ending with meat sauce and remaining mozzarella.

Cover tightly with aluminum foil and bake for 35 minutes. Remove foil and bake for another 10-15 minutes until the top is golden brown.

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