Creamy Leek Sauce with Gruyere

Ingredients:

1 1/2 tablespoons unsalted butter
1 clove garlic
1 large leek, thinly sliced (white part only)
3 tablespoons flour -- sifted
salt and white pepper
nutmeg
3/4 cup milk -- hot
2 cups heavy cream
1/4 pound Gruyere cheese -- grated

Instructions:

Melt butter in a saucepan over low heat and add garlic and sliced leek. Slowly cook sliced leek, stirring often, until golden and softened, about 8 to 10 minutes. Stir in the flour and season to taste with salt, pepper and nutmeg. Cook until the flour changes color just slightly.
Remove garlic clove and then gradually add the milk, stirring all the time. When sauce is smooth and thick, pour in cream. Bring back to the boil, lower the heat and cook for 5 minutes.
Add Gruyere and cook, stirring, until cheese has melted. Remove from heat and cool slightly before serving. This sauce keeps well refrigerated for up to four days.
Recipe source "The New Pasta Cookbook"