Preheat your oven to 375°F (190°C).

Cook the lasagna noodles in a large pot of boiling salted water according to the package instructions until al dente, about 8-10 minutes. Drain and cool in cold water.

In a skillet over medium heat, cook the ground beef until non-pink, breaking it into pieces. Add diced onion, minced garlic, sea salt, black pepper, and oregano; stir for 3-4 minutes until onions are translucent. Pour in marinara sauce and simmer for a few minutes.

Spread 1/2 cup of the meat sauce on the bottom of a 9x13-inch casserole dish.

In a mixing bowl, combine ricotta cheese, large egg, shredded Parmesan, 1 cup shredded mozzarella, and parsley. Stir until creamy.

Lay out each noodle, spread cheese mixture over it, spoon some meat sauce on top, and roll tightly. Place seam-side down in the casserole dish.

Pour remaining meat sauce over the rolled noodles and sprinkle with the remaining mozzarella cheese. Cover with foil.

Bake covered for 40 minutes, then broil for 2-3 minutes until golden. Keep an eye on it to prevent burning.

Let rest for 5-10 minutes before serving. Garnish with extra parsley if desired.