Cook the pasta shells in boiling water, according to package directions, until al dente. Drain pasta and set aside.

In a bowl combine 1/2 cup Parmigiano Reggiano cheese, 1 cup mozzarella cheese, ricotta cheese, spinach and egg until blended.

Pour about 3/4 cup of marinara sauce into the bottom of a 9×13 baking dish. Stuff each of the jumbo pasta shells evenly with cheese mixture.

Drizzle remaining marinara sauce on and between the pasta shells. Top with remaining Parmigiano Reggiano and mozzarella cheese. Cover baking dish with foil and bake at 375° for 25 minutes. Remove foil and bake an additional 10 minutes until the shells begin to slightly brown and the cheese is melted.

Remove from oven, allow to cool a 3-5 minutes and enjoy!