Preheat oven to 480°F.
In a pan, heat butter on low heat. Add flour and stir for 2 minutes.
Bring to a boil and pour warm milk. Mix well and add red chili flakes, onions, black pepper powder, salt, parsley and stir to combine.
Add the sliced franks and mix well.
Add ½ cup cheese to the pan and stir on low heat.
Transfer mixture to a baking dish, and top with remaining cheese and bread crumbs.
Bake in the preheated oven for 5 minutes.
Garnish with chopped parsley and serve hot.