|Onions||2 Medium, chopped|
|Chicken stock||4 Fluid Ounce|
|Milk||1 1⁄2 Pint|
|Cheddar cheese||12 Ounce, grated|
|Gruyere cheese||3 Ounce, grated|
|Prepared mustard||1⁄2 Teaspoon|
|Black pepper||1⁄4 Teaspoon|
|Paprika||1 1⁄2 Teaspoon|
|Worcestershire sauce||1 Teaspoon|
In a large heavy saucepan, melt the butter over moderate heat.
When the foam subsides, add the onions and cook for 8 to 10 minutes or until they are golden.
Stir in the flour and cook, stirring, for 2 to 3 minutes.
Remove the pan from the heat and gradually stir in the stock.
When the mixture is smooth, stir in the milk.
Add the cheese and the mustard.
Return the pan to low heat.
Cook, stirring, until the cheese melts.
Do not allow the soup to reach boiling point.
Remove the pan from the heat.
Season with salt, pepper and paprika.
The amount of seasoning depends on the strength of the cheese, and it is advisable to taste and season as the soup requires.
Add the Worcestershire sauce and serve.