1) Prepare pasta according to package directions; drain.
2) Combine mozzarella cheese, ricotta cheese, onion, oregano, basil, salt and pepper, stir together until well blended.
3) Pour about 1 cup tomatoes over bottom of 13 x 9 x 2-inch baking pan, breaking up tomatoes with a fork.
4) Spoon a round tablespoon of cheese mixture into each Paccheri and place open-side up in an even layer in the pan.
5) Pour remaining tomatoes over and around Paccheri.
6) Cover pan with foil, bake at 375o F for about 25 minutes until heated through, and serve.