Preheat your oven to 375°F.
Cook the rigatoni according to package instructions until al dente. Drain and set aside.
In a large mixing bowl, combine the ricotta cheese, half of the mozzarella cheese, Parmesan cheese, egg, garlic powder, Italian seasoning, salt, and pepper. Mix until well combined.
Add the cooked rigatoni and chopped spinach to the cheese mixture. Stir until the pasta is evenly coated.
Grease a 9x13 inch baking dish with olive oil. Pour half of the marinara sauce into the bottom of the dish.
Spoon the rigatoni mixture over the sauce, spreading it evenly. Top with the remaining marinara sauce and sprinkle the rest of the mozzarella cheese on top.
Cover the dish with aluminum foil and bake for 25 minutes.
Remove the foil and bake for an additional 10-15 minutes, or until the cheese is bubbly and golden.
Let it cool for 5 minutes before serving.
