Heat oven to 180C/Gas 4.
Melt 110g butter in a large saucepot over medium heat. Add flour and cook, stirring, for 1 minute. Whisk in the warmed milk and bring to a boil, continue to whisk constantly. The mixture will thicken as the heat increases. Continue to stir while adding
the dry mustard, nutmeg, cayenne, salt, pepper, hot sauce and Worcestershire. Stir in the 3 cups of Cheddar until it melts.
Pour the cheese sauce over the noodles and add to a 3.6L casserole dish.
Sprinkle the chips, bacon and Parmesan on top and bake for 35 minutes.