Preheat oven to 375°F (190°C).
In a large skillet over medium-high heat, brown the lean ground beef with diced onions until the meat is no longer pink. Add minced garlic and cook for 1 minute.
Stir the marinara sauce, Italian seasoning, salt, and pepper into the beef. Simmer for 5 minutes then remove from heat.
In a food processor or blender, pulse the cottage cheese and egg until smooth to create a high-protein ricotta alternative.
In a 9x13 inch baking dish, spread 1/2 cup of the meat sauce on the bottom. Layer 3 to 4 lasagna noodles over the sauce.
Spread 1/3 of the cottage cheese mixture over the noodles, followed by a layer of chopped spinach, and 1/2 cup of mozzarella cheese.
Repeat the layers (sauce, noodles, cottage cheese, spinach, mozzarella) twice more.
Top with the remaining meat sauce, the final 1/2 cup of mozzarella, and the Parmesan cheese.
Cover the dish with aluminum foil and bake for 25 minutes.
Remove the foil and bake for an additional 15-20 minutes until the cheese is golden and bubbling.
Let the lasagna rest for 10 minutes before slicing to allow the layers to set.