White sauce is known as béchamel in France or besciamella in Italy and is an important basic sauce that is used in many dishes like lasagna. White sauce is made using only three ingredients: milk, butter, and flour. Most recipes will tell you to add the milk slowly while stirring. This is in fact a difficult method with a high risk of lumps and it will take more time. In this post I will teach you a much easier method.
The weight of the butter and flour should be 10% of the milk. To give you a few examples:
- for 250 ml (1 cup) of milk you will need 25 grams (2 1/2 tablespoons) of flour and 25 grams (2 tablespoons) of butter
- for 500 ml (2 cups) of milk you will need 50 grams (1/3 cup) of flour and 50 grams (3 1/2 tablespoons) of butter
- for 1 litre (4 cups) of milk you will need 100 grams (2/3 cup) of flour and 100 grams (7 tablespoons) of butter
It is easier (but not necessary) to heat the milk first (I always do this in the microwave, but a saucepan would work as well) until small bubbles are visible around the edge. So the milk should not boil, just be hot. (You can skip this step, but then you will have to stir for a longer time after adding the milk to the roux.)
Melt the butter in a saucepan.
When the butter foams, turn the heat to low and add the flour.
Stir for about a minute over low heat and make sure the butter and flour are well mixed. This is called a roux, which can be used to thicken other sauces as well. It can be cooked longer to make a brown roux, but for a white sauce you will need a white roux. (Many recipes tell you to cook until the roux until it no longer tastes like raw flour, but I have never needed to taste the roux.)
Now you add all the milk at once (either hot or cold, both will work). Be brave, just keep pouring quickly.
Once you’ve added all of the milk, whisk energetically until there are no more lumps. This should be very easy.
Increase to medium heat and keep stirring constantly until the white sauce has the desired thickness, making sure to scrape along the bottom while stirring so the sauce doesn’t stick and burn. (This step is a lot quicker if you used hot milk.) Turn off the heat as soon as it has the desired thickness. You may need to lower the heat if it starts to boil too vigorously.
You can now season the white sauce to taste with salt, and if you like also with freshly ground white pepper and/or freshly ground nutmeg.
You can use it straight away. If not, cover it with plastic wrap/cling film such that the plastic actually touches (clings to) the surface of the white sauce. This will prevent a skin from forming.