Preheat your oven to 375°F (190°C).
Cook the lasagna noodle in boiling salted water according to package directions until al dente, then drain and set aside.
Heat the olive oil in a skillet over medium heat and sauté the diced onion and minced garlic until translucent and fragrant.
Add the ground beef to the skillet, seasoning with sea salt, black pepper, and dried oregano, and cook until fully browned.
Pour the marinara sauce into the skillet with the beef and simmer for 5 minutes to allow the flavors to meld.
In a small mixing bowl, stir together the ricotta cheese and half of the parmesan cheese.
In a small individual-sized baking dish, spread a spoonful of the meat sauce on the bottom, followed by a piece of the cooked noodle (cut to fit).
Layer on half of the ricotta mixture, more meat sauce, and another piece of noodle, repeating until all ingredients are used.
Top the final layer with the shredded mozzarella and the remaining parmesan cheese.
Bake for 20-25 minutes until the sauce is bubbling and the cheese on top is melted and lightly golden.