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Mac Sauce (Béchamel 101)

This classic Béchamel sauce, often referred to as a simple white sauce, is a fundamental skill for any home cook. Known as one of the French mother sauces, this vegetarian staple provides a silky, creamy base for a multitude of comforting British favourites. By gently cooking butter and flour into a roux before whisking in warm milk, you create a versatile foundation that delivers a rich mouthfeel and a subtle, savoury flavour to your cooking.

Whether you are preparing a traditional macaroni cheese, layering a hearty lasagne, or topping a seasonal vegetable gratin, this dependable recipe ensures a lump-free finish every time. It is a brilliant make-ahead component for busy weeknights, as it stores well in the fridge and can be easily loosened with a splash of milk when you are ready to melt in your favourite cheddar or gruyère.

Continue reading below

Ingredients for Mac Sauce (Béchamel 101)

  • 725ml whole milk

  • 120ml unsalted butter

  • 60g plain flour

  • 2 teaspoons kosher salt or 1 teaspoon table salt

How to make Mac Sauce (Béchamel 101)

Heat the milk in a pot over medium heat until it just starts to bubble, but is not boiling, 3 to 4 minutes. Remove from the heat.

Heat the butter over medium heat in a separate, heavy-bottomed pot. When the butter has just melted, add the flour and whisk constantly until the mixture turns light brown, about 3 minutes. Remove from the heat.

Slowly pour the warm milk, about 240ml at a time, into the butter-flour mixture, whisking constantly. It will get very thick when you first add the milk, and thinner as you slowly pour in the entire 725ml . This is normal.

Once all the milk has been added, set the pot back over medium-high heat, and continue to whisk constantly. In the next 2 to 3 minutes the sauce should come together and become silky and thick. Use the spoon test to make sure it's ready: Dip a metal spoon into the sauce—if the sauce coats the spoon and doesn't slide off like milk, you'll know it's ready. You should be able to run your finger along the spoon and have the impression remain. Add the salt.

The Mac Sauce is ready to use immediately and does not need to cool. Store it in the fridge for a day or two if you want to make it ahead of time—it will get a lot thicker when put in the fridge, so it may need a little milk to thin it out a bit when it comes time to melt in the cheese. Try melting the cheese into the sauce first, and if it is too thick then add milk as needed.

Disclaimer

While every effort has been made to ensure the information is accurate and up to date, individual needs may vary and dietary requirements can differ based on personal health conditions. Always check food labels and allergen information before preparing or consuming any recipe. If you have specific health concerns, allergies, intolerances, or are following a medically prescribed diet, seek advice from your GP, pharmacist, or a registered dietitian before making significant changes to your diet or lifestyle.

Article history

The information on this page is peer reviewed by qualified clinicians.

  • 16 Jan 2026 | Originally published

    Authored by:

    UK recipe editors

    Peer reviewed by

    UK recipe editors
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