Baked Penne - Vegeterian

1 lb penne pasta 3 tablespoons olive oil 1 small onion , finely chopped 1 large ripe tomato , peeled, seeded, and finely chopped 3 tablespoons all-purpose[...]

8 ounces penne 1 cup frozen peas, thawed 1 cup cherries or 1 cup grape tomatoes , halved 2 cups bottled pasta tomato sauce 2 cups shredded low fat mozzarella[...]