Put the cheddar into a pan and add the milk. Slowly melt them together over a low heat but do not allow the mix to boil or the cheese will separate.
When the mixture is smooth and just starting to bubble add the flour, breadcrumbs and mustard and cook for a few minutes, stirring, over a low heat.
When the mixture comes away from the sides of the fan and begins to form a ball shape add the Worcester sauce, salt and pepper and set aside to cool.
When cold, place in a food processor, turn on the motor and slowly add the eggs and the egg yolks. If you dont have a food processor beat vigorously with a wooden spoon.
When the eggs are mixed in chill for a few hours before using.