In a large pot, bring salted water to a boil. Add the lasagna noodles and cook according to package instructions. Drain and lay flat on a clean towel.
In a mixing bowl, combine ricotta cheese, 1/2 cup of grated Parmesan cheese, chopped spinach, egg, oregano, garlic powder, and a pinch of salt and pepper. Stir until smooth.
In a 9x13 inch baking dish, spread a thin layer of marinara sauce. Arrange 3 lasagna noodles over the sauce. Spoon 1/3 of the ricotta mixture over the noodles, followed by 1/3 of the mozzarella cheese and another drizzle of marinara sauce. Repeat this layering process two more times, finishing with noodles on top, marinara sauce, and remaining mozzarella cheese.
Sprinkle the remaining 1/2 cup of grated Parmesan cheese over the top. Cover with aluminum foil (spray the underside with cooking spray to prevent sticking) and bake for 25 minutes.
Remove the foil and bake uncovered for an additional 15-20 minutes until the cheese is bubbly and golden brown.
Let the lasagna rest for about 10 minutes before slicing. Garnish with fresh basil leaves and serve warm.
Notes
Let the lasagna rest before slicing for easier serving.