In a large stock pot, fry the bacon pieces until crisp. Remove from the pan, leaving the drippings, and set aside.
Peel and chop the potatoes into bite sized chunks. Slice the scallions very thin and separate the greens from the whites.
Place the potatoes and white scallion pieces into the stock pot and cook over medium heat until the scallions have softened, 2 or 3 minutes.
Sprinkle in the flour and cook, stirring constantly, for about 1 minute.
Pour in the milk, chicken stock, Old Bay, thyme, parsley, cayenne, salt, and pepper, stirring well. Bring to a boil over medium heat, stirring occasionally.
Reduce heat to low and simmer for 12-15 minutes or until the potatoes are tender. Add corn (If using fresh corn, cut from the cob with a sharp knife. Use the back of your knife to release the pulp from the cob.), chicken, and green chiles. Cook over low heat until heated through, about 5 minutes. Garnish with scallion greens, bacon, and cheddar cheese.