Preheat your oven to 375°F (190°C).
Cook the lasagna noodles in boiling water until al dente, then drain and set aside.
In a bowl, combine ricotta cheese, 1/2 cup of mozzarella, Parmesan, spinach, egg, garlic powder, salt, and pepper.
Spread a thin layer of marinara sauce on the bottom of a baking dish.
Lay a cooked noodle flat and spread a generous amount of the cheese mixture on top.
Roll the noodle tightly and place it seam-side down in the baking dish.
Repeat the process with the remaining noodles and filling.
Top the rolled noodles with the remaining marinara sauce and sprinkle the rest of the mozzarella cheese on top.
Cover the dish with foil and bake for 20 minutes.
Remove the foil and bake for an additional 10 minutes until golden and bubbly.