Preheat your oven to 375°F (190°C).
Cook the whole grain lasagna noodles in boiling water according to package directions until al dente; drain and set aside.
In a skillet over medium heat, brown the ground beef with diced onions and minced garlic until the meat is cooked through and onions are translucent.
Stir in the marinara sauce, dried oregano, sea salt, and black pepper; simmer on low for 5 minutes.
In a small mixing bowl, combine the ricotta cheese, chopped fresh spinach, chopped parsley, and the beaten egg until smooth.
In a small individual baking dish, spread a thin layer of the meat sauce on the bottom.
Place one lasagna noodle over the sauce, trimming to fit if necessary, then spread the ricotta mixture evenly over the noodle.
Add another layer of meat sauce, the second noodle, and the remaining meat sauce.
Sprinkle the shredded mozzarella cheese evenly over the top.
Bake for 20-25 minutes until the cheese is melted and golden and the sauce is bubbling.