Start by thawing the frozen spinach completely, then drain it well. Use your hands or a clean kitchen towel to squeeze out as much excess liquid as possible so the lasagna doesn’t turn watery.
In a medium bowl, mix together the cottage cheese, spinach, Parmesan, egg, garlic powder, onion powder, salt, pepper, and nutmeg until everything is well combined.
Preheat your oven to 350°F and lightly spray a 9x9-inch baking dish with olive oil spray so nothing sticks. Then, spread a thin layer of marinara sauce on the bottom of the dish, and place 2 no-boil lasagna noodles on top.
Spread half of the cottage cheese spinach mixture evenly over the noodles, making sure it reaches the edges, then sprinkle with some mozzarella cheese.
Add another layer of noodles, followed by a layer of marinara sauce, then spread the remaining cottage cheese mixture over the top.
Spoon a little more marinara over the filling, add the final layer of noodles, and top with the rest of the marinara sauce. Finish with the remaining mozzarella cheese, spread evenly over the top so it melts nicely in the oven.
Cover with foil and bake at 350°F for 40-45 minutes until heated through and bubbling.
Remove the foil and bake for another 5-10 minutes so the cheese on top gets melted and lightly golden. Once done, let the lasagna rest for 10-15 minutes before slicing and serving.