Make a simple bechamel sauce with the flour, butter, milk.
melt butter on medium heat, stirring in flour and cooking until golden.
add cold milk, turn up the heat to med/high, and stir constantly to avoid scalding, stir until thickened.
turn heat back to med and add GRATED red leicester cheese (has to be red leicester, won't taste right or be the right color other wise).
stir in red leicester, add 100g of soft cheese, stir through until melted and smooth.
add 1/2 tbs of chopped (really fine) chili's or red chili paste and stir in until smooth.
take off heat and serve.
also nice cold, has been used as the sauce for mac and cheese quite successfully, baked potato topping with bacon (kind of tastes like wendy's) and also -- if you want you can stir in some jalapeño peppers. (Make sure you drain them if canned.).