Preheat oven to 350.
Bring a large pot of salted water to a boil. Cook the lasagna sheets according to package directions. Drain and set aside.
While the pasta is cooking, put together the filling. Mix together the ricotta, spinach, egg, parmesan, oregano, salt and pepper until thoroughly combined.
Place 1/4 cup of sauce in the bottom of a baking dish.
Lay out one sheet of lasagna and spread 2 tablespoons of the filling mixture and then sprinkle with a layer of mozzarella cheese.
Roll up a lasagna sheet and place wavy/open side up in the dish. Repeat with all lasagna sheets until the pan is full.
Spread 2 cups of sauce over the top off the lasagna.
Cover and place in the oven for 30 minutes. Uncover, sprinkle on remaining mozzarella cheese and bake for another 10 minutes.
Remove, sprinkle with basil and serve.