Preheat the oven to 375°F (190°C).

Boil the lasagna noodles in a large pot of salted water per package directions until al dente. Drain and arrange the noodles flat on parchment paper to prevent sticking.

Heat olive oil in a large skillet over medium heat. Add the chopped onion and minced garlic, sautéing until fragrant and translucent.

Incorporate the ground beef, cooking until browned throughout. Drain any excess fat.

Stir in 1 cup of marinara sauce with the cooked beef mixture and allow it to cool slightly.

In a separate bowl, blend the ricotta cheese, egg, 1/4 cup of the grated Parmesan, salt, and black pepper until creamy and smooth.

Spread a layer of the ricotta mixture onto each lasagna noodle. Spoon a portion of meat sauce evenly over the cheese, and carefully roll up each noodle with the seam on the bottom.

Coat the base of a large baking dish with the remaining marinara sauce. Arrange the rolled noodles seam-side down in the dish.

Sprinkle with mozzarella cheese and the remaining Parmesan. Cover the dish tightly with foil and bake for 20 minutes.

Remove the foil and bake for an additional 10 minutes until the cheese is golden and bubbling.

Sprinkle with fresh parsley before serving hot.