Ingredients:

1/8 cup butter
1 heaping tbsp flour
1 1/2 cups hot broth or milk
pepper, salt

Ingredients:

Melt butter, add flour and cook, stirring rapidly, for a few minutes, until the paste acquires some colouring (the French call it roux).
Gradually add broth or milk and cook over low fire, stirring continuously until thickened.
Add salt and pepper and reduce to about 1 cup ( duration: about 30 minutes)