Preheat oven to 350F. Spoon the marinara sauce onto the bottom of a 9X13 baking dish.
Cook pasta shells according to package directions. Drain. Drizzle a baking sheet with oil and set pasta shells on it to cool.
Meanwhile, in a large bowl, mix ricotta, spinach, Parmesan, mozzarella, basil, oregano, salt and pepper. Stir in an egg until well combined.
Arrange cooled pasta shells in the baking dish. Spoon ricotta mixture into each shell. Sprinkle with more mozzarella cheese.
Bake in the oven for 25 minutes. Serve.
Note: Metric ingredient measurements are provided as a courtesy using a third-party calculator and are rounded to the nearest unit. The recipes provided on this site have not been tested with metric measurements and their accuracy cannot be verified.
The nutritional information provided is based on third-party calculations and is an estimate only. Accurate nutritional facts will vary based on the particular brands used, portion sizes, measurement accuracy and more.