Boil water in a large pot, add salt, cook jumbo shells until tender but still firm, then drain carefully and cool slightly.

Spread some marinara sauce on bottom of baking dish, just enough to lightly cover surface and prevent shells sticking during baking.

In a large bowl combine ricotta, mozzarella, parmesan, egg, parsley, basil, salt, and pepper until smooth, creamy and well blended together.

Spoon cheese filling into each shell gently, filling generously but not overflowing and place stuffed shells open side up neatly.

Pour remaining marinara sauce over shells evenly, covering lightly so pasta stays moist and cheese filling bakes perfectly inside.

Cover dish with foil, place in preheated oven, and bake until hot and bubbly, letting flavors melt together beautifully inside.

Remove foil for last minutes, let cheese brown slightly on top, and allow sauce to thicken gently around shells while finishing.

Let dish rest a few minutes after baking so shells set slightly, making serving easier and flavors more balanced and rich.