Cook fries according to package instructions. Place in a large bowl, then sprinkle with garlic salt and set aside.
Meanwhile, melt butter in a medium pan over medium heat, then add flour and whisk until blonde. Whisk in milk, Worcestershire and sriracha and bring to a simmer, then cook until thickened, 3 to 5 minutes. Whisk in both cheeses until melted. Adjust seasoning with salt and pepper.
Place a couple slices of turkey on the griddled Texas toast, then a pile of French fries; ladle the cheese sauce over the entire thing. Garnish with some parsley and some pickled peppers.