Method : 

• Warm the milk in a microwave or a separate pan , do not boil just get it hot.
• Melt the butter in to a medium size saucepan.
• When the butter is melted add the flour and mix into a paste.
• Slowly add the warm milk a quart at a time and mix together with a wire whisk, adding more milk until the mixture is at a thick consistency - A thick sauce. This should require about 3 quarters of the milk. 
• Add the Beer , Worcestershire sauce & Mustard to the pan and mix together. 
• When the sauce it bubbling and hot add your cheese and mix in. Allow the cheese to melt fully then remove the sauce from the heat and decant into a cooling dish.
• Leave to cool for a few hours until the Rarebit is set.

   ' Use this paste to spread on fresh crusty toast and melt under the grill until brown ,serve with poached egg's and crispy Bacon .... '