Fill a large pot with water.
Add salt and bring to boil.
Cook shells for 9 minutes.
They should be slightly firm.
Drain and let them cool.
Mix ricotta in a bowl.
Add mozzarella and parmesan.
Crack in the egg.
Add Italian seasoning.
Stir until smooth and creamy.
Spread one cup of sauce.
Cover the bottom evenly.
This stops shells from sticking.
Spoon filling into each shell.
Use about two tablespoons each.
Place them in the dish.
Keep them close together.
Pour remaining sauce on top.
Sprinkle extra mozzarella over shells.
Cover dish with foil.
Preheat oven to 375°F.
Bake covered for 25 minutes.
Remove foil and bake 10 more.
Cheese should be bubbly and golden.