Bring a large pot of salted water to a boil.

In a mixing bowl, combine ricotta cheese, egg, oregano, garlic powder, salt, and pepper.

Preheat your oven to 375°F (190°C).

Spread a thin layer of marinara sauce on the bottom of the baking dish.

Place four cooked lasagna noodles over the sauce, slightly overlapping them.

Spoon half of the ricotta mixture over the noodles, spreading it evenly.

Continue layering with marinara sauce, noodles, ricotta, and mozzarella, ending with noodles and sauce on top.

Top the last layer with remaining mozzarella and Parmesan cheese.

Bake in the preheated oven for 45 minutes.

Let the lasagna rest for 15 minutes before slicing.