Preheat your oven to 375°F (190°C).
Boil the lasagna noodles in salted water until al dente, then drain and set aside.
In a skillet over medium heat, brown the ground beef with minced garlic, sea salt, and black pepper until no longer pink.
Stir in the marinara sauce, dried oregano, and baby spinach, simmering for 3 minutes until the spinach is wilted.
In a small bowl, stir the ricotta cheese until it reaches a smooth, spreadable consistency.
In a small oven-safe baking dish, spread a spoonful of the meat sauce on the bottom, followed by a piece of noodle.
Layer with a dollop of ricotta and more meat sauce, repeating the layers until all ingredients are used.
Finish with a final layer of meat sauce and a sprinkle of parmesan cheese.
Bake for 15 to 20 minutes until the cheese is golden and the sauce is bubbling.