In a large pot over low heat, add the shredded chicken and stock. Heat gently for 15 minutes to reheat and rehydrate the chicken.
In a large pan with straight sides on medium heat, add the butter, oil, onions, a pinch of salt and a hefty amount of pepper. Cook until the onions are tender, 5 to 8 minutes. Then, add the mustard, red chili flakes, thyme and garlic. Cook a few minutes to combine, then add the flour and cook until you can't smell the flour anymore, 2 to 3 minutes. Strain the chicken stock from the pot of chicken (reserve the chicken) and slowly add the stock to the pan, stirring. Cook until thickened to a gravy consistency, 5 to 8 minutes.
Meanwhile, fry the crinkle fries according to the package instructions.
Toss the parsley with the reserved chicken. In a shallow serving bowl, add the fries, some cheese, the chicken, more cheese, the gravy, bacon and scallions.