Step 1

Heat butter in a saucepan over medium heat for 2 minutes or until melted and foaming. Add flour. Cook, stirring with a wooden spoon, for 1 minute or until mixture bubbles. Remove pan from heat. Slowly add milk, 1/4 cup at a time, stirring constantly to prevent lumps forming.

Step 2

Return pan to medium heat. Cook, stirring, for 5 minutes or until sauce boils and thickens. Stir in cheese until smooth. Remove pan from heat.