Cook pasta shells with a little bit of olive oil to help keep them from sticking. (I brush a little oil on the bottom of each shell) Rinse in cold water when cooked.
Place entire tub of cream cheese in a bowl. Shred cooked chicken and add to cream cheese. (If you place hot shredded chicken on top of cream cheese, it makes it much easier to mix!)Add 1 1/4 cup shredded cheese. Mix all together. Use as stuffing for pasta shells. Line shells up in glass 9x13 baking dish. Top with tomato sauce and remaining shredded cheese. Sprinkle with parmesan and Italian seasoning, if desired. Bake 30-40 minutes, or until heated through and cheese has melted.