Ingredients:
40g butter
25g plain flour
600ml milk
300ml stock
1 onion, finely chopped
1 small leek, chopped
1 celery stick, finely chopped
pinch of ground mace
2 eggs, separated
50g cheese, grated
salt and freshly-ground black pepper, to taste
chopped parsley, to garnish
Method:
Melt the butter in a heavy-based pan. Scatter over the flour then cook gently, stirring constantly, for 2 minutes. Gradually whisk in the milk until smooth then add the stock. Bring the mixture to a boil, stirring constantly, then add the vegetables and mace. Season to taste with salt and black pepper and stir well. Bring to a simmer, cover the pan and cook gently for 30 minutes.
Beat the egg yolks in a bowl then whisk in two ladlefuls of the hot soup to temper. Stir this into the soup pan then add the cheese. Heat the mixture gently, stirring until all the cheese has melted.
Add the egg whites to a clean and dry bowl then whisk until they form stiff peaks. Fold half the egg whites into the soup then divide the remainder between warmed soup bowls. Ladle over the soup, garnish with parsley and serve.
