Ingredients

•   butter
•   flour
•   milk
•   salt and pepper

Method

1. Gently melt butter in a pan. Add flour and stir with a wooden spoon to make a paste (called a roux).
2. Cook roux over a low heat for 1-2 mins until it takes on a 'sandy' texture.
3. Add milk gradually, whisking to make a smooth sauce.
4. Return to heat and bring to boil, stirring. Simmer for a few mins, stirring, until sauce thickens. Season.