1 small onion, diced
2 tablespoons olive oil
1 28-ounce can crushed tomatoes
1 pound large pasta shells
8 ounces mozzarella
1 pound ricotta cheese
3/4 cup grated parmesan, divided
salt & pepper to taste
1/2 cup chopped pancetta
Preheat oven to 400 degree F.
Heat 2 tablespoons oil in a medium saucepan. Add onion, cook until softened, about 2-3 minutes. Add the tomatoes, season with salt & pepper. Simmer sauce for 10 minutes.
Meanwhile, bring 4 quarts of water to a boil in a pasta pot or large saucepan. Add a tablespoon of salt and pasta shells. Cook shells until al dente. Drain.
Grate mozzarella on the large holes of a box grater. In a medium mixing bowl, mix together the ricotta, grated mozzarella, and 1/2 cup of the parmesan. Season to taste with salt & pepper.
Add a few spoonfuls of tomato sauce to the bottom of a large casserole dish, enough to coat it completely. Holding one of the cooked pasta shells in your hand, fill it with the cheese mixture. Place it in the casserole dish with the opening facing up. Repeat with the rest of the shells and filling, placing them in one layer. Spoon tomato sauce over shells. Sprinkle the rest of the grated parmesan. Sprinkle the pancetta.