Preheat your oven to 350F with an oven rack in the middle position.
Bring a large pot of water to a boil and add in a tablespoon of salt. Cook the jumbo pasta shells as per directed on the package. Drain the cooked shells and set aside.
In a large bowl, whisk together the softened cream cheese, the buffalo sauce and the ranch dressing. (This works best if you microwave the cream cheese for 45 seconds to soften it.)
Use a spoon to fill 24 cooked jumbo shells with the buffalo chicken mixture. Place them in a greased baking dish.
Sprinkle the grated cheese over the filled shells. Place the baking dish in the preheated oven for 15-20 minutes, or until lightly golden on top.
Take the baked shells out of the oven and let rest for 5 minutes. Drizzle the shells with buffalo sauce and sprinkle them with the chopped green onion.