Bechamel sauce: how to keep it lump free AND take it to another level

Bechamel, also known as white sauce, is the foundation of many wonderful sauces and dishes, especially in French and Italian cuisine. But it can be problematic for inexperienced cooks. And if you already know how to make a good one, do you know how to step it up to a great bechamel sauce?

To understand the way that different cooks approach making one, I reviewed 16 recipes for bechamel sauce. Even though it is a fairly simple sauce, there were a number of interesting and unexpected differences amongst the recipes.

Before we dig into those though, a quick definition.

What is bechamel sauce?

In it’s simplest form, bechamel sauce is essentially milk thickened with flour. The flour is cooked in fat (more on this later), and some authors add two or three flavours, but otherwise it’s not much more than that.

So the typical ingredients are simply:

Flour
Butter
Milk
Salt & pepper to season

Although it is a fairly simple sauce, it is a little tricky to make if you haven’t done it before.

How do you make bechamel sauce?

Even though there is some variation amongst these recipes, the fundamental process is the same:

Make a roux of flour and butter.
Add milk.
Simmer until thickened.

It sounds simple, but it can be finnicky for the uninitiated, especially when it comes to lumps. So let’s have a look at each step.

Closeup of the tip of a wooden spoon in a bubbling flour and butter roux.

Making a roux

The thickening agent in bechamel sauce is flour. But if you’re wondering why you can’t just add flour to warm milk to thicken it, there are a couple of reasons:

Flour tends to clump when mixed with water, especially when hot.
Raw flour has a distinct taste that’s not very pleasant. This can be quite noticeable in a simple sauce like a bechamel.

As a result, the best way to thicken a sauce with flour is to first create a roux, which is flour cooked in fat. This goes a long way to solving the two potential issues with using flour as a thickener.

Preventing clumping with a roux

When they’re cooked in hot fat, the flour particles become coated in the fat. This allows them to slide over one another, reducing clumping when they start to swell with the introduction of a liquid.

So a primary goal of making a roux is to ensure all of the flour is coated in fat. There are two keys to this:

Making sure you have enough fat to coat all the flour.
Stirring constantly to bring all of the flour into contact with the fat.

How much fat?

The traditional approach to ensuring you have enough fat is to use equal parts flour and fat by weight.

That said, some authors default to equal parts by volume (typically 1 tbsp butter per tbsp of flour). This will still work, because butter is denser and heavier than flour. A tablespoon of butter weighs almost twice what a tablespoon of flour does. So there’ll be plenty of fat to coat your flour.

A few authors use less butter than flour (by volume), but because it weighs more they still have ample fat to reduce clumping.

When there’s enough fat in the roux, with plenty of stirring you can make sure the flour is all thoroughly coated. Most authors recommend you do this with a whisk, which helps to separate the flour particles.

But a roux doesn’t just help with clumping.

Improving the taste of the flour

The floury taste of raw flour is starch. Cooking flour at a high enough temperature breaks down starch into dextrins, which have a sweeter taste.

Breaking down enough flour to make a difference takes a little time. Interestingly, the recipes vary considerably in how much time they allow for it.

Nine of the 16 authors suggest cooking your roux for only one or two minutes. And three more only cook it until it’s come together in a paste (usually less than a minute). This brief cooking process will likely convert some of the starch, but arguably not enough to make a meaningful difference to the overall taste.

Two authors, Lisa from Gourmet Traveller and Faith from The Kitchn, recommend cooking your roux for up to ten minutes. These longer cooking times will definitely have a greater impact on the floury taste of the roux.

Keep in mind that the focus of many authors these days is shortening cooking times to make recipes more suitable for busy people. This is an admirable goal, but will of course sometimes require compromises.

Ultimately though taste is completely personal. Some people probably don’t notice the raw taste of the flour. Others likely find it overpowering. The good news is your roux will still work either way, so the choice is yours.

If you are attuned to the raw taste of flour and decide to cook your roux for a longer time, it’s worth noting that dextrins are not as good at thickening as starch. So the longer you cook the flour, the less it will thicken your sauce. This is why a dark roux (cooked for a long time, taking on a dark colour and a significant flavour change) is not as good at thickening as a white or a blond roux.

A note of caution about butter

The most commonly used fat for making a roux is butter. In fact, all 16 of the recipes I reviewed use butter.

Butter is popular because it’s easily accessible and it adds a delicious rich flavour to your sauce. But there are a couple of potential issues with butter that may cause troubles if you’re new to making a roux.

The first is water. Water can cause your roux to seize up, clumping into impenetrable masses of flour. And most commercially-available butter is about 15% water. It’s not much, but this can cause your flour to start forming small clumps if you’re not careful.

There are a couple of ways to avoid this potential problem:

Use a fat that contains no water. You can make a roux with any cooking oil. Or if you like the taste of butter, ghee (clarified butter) contains no water.
If you’re using butter, melt it over very low heat and let it bubble away for a few minutes. The bubbling is the water boiling off. With time, the bubbling will stop, meaning the water has all evaporated. Low heat is important though, because you don’t want to brown (or burn) the butter.

The second issue to be aware of with butter is it’s low smoke point. Butter will burn at a much lower temperature than vegetable oil, or even clarified butter. So make sure you keep an eye on the heat. Too much and you could ruin your roux.

Adding milk to the roux

Once your roux is cooked to your liking, it’s time to add the milk.

How much milk

The thickness of your bechamel sauce will depend on the ratio of flour to milk.

The 16 recipes average two tablespoons of flour per cup of milk, but they vary from as little as just over one to as much as three.

Depending on who you read, a classic bechamel is made with between two and three tablespoons of flour per cup of milk.

For a runnier sauce, you can go as low as one tablespoon per cup. And if you want a really thick sauce you can go up to four.

How to add the milk

Even though the flour is coated in fat, without careful technique it can still clump when a large amount of liquid is added.

The authors of these recipes take one of two different approaches to adding the milk to their roux.

The most popular method by far is to add the milk gradually, either in small amounts or a slow steady stream. Fourteen authors take this approach. This allows the milk to be incorporated more slowly, limiting the opportunity for clumps to form. It also stops the milk from cooling the roux too much.

The other two authors heat their milk and add it to the roux all at once. By heating it, they’re preventing the milk from cooling the roux, causing the fat to firm up. While this approach clearly works for them, if you’re not as confident making a white sauce the safer method is to add your milk gradually.

Whichever approach you take, the key here is stirring. Stir, stir, stir! By keeping the flour and the milk moving, you’re limiting the opportunity for clumps to form. And if you added cold milk, you’re also preventing the milk from cooling the roux too much.

Flavourings for a bechamel sauce - nutmeg, black peppercorns, cloves, bay leaves and an onion.

What about flavours?

A common way to add flavours to a bechamel is by infusing them into the milk beforehand. The traditional way is by heating the milk together with the chosen ingredients, and then simmering it or simply allowing it to cool.

Nine of the recipes call for one or more flavouring ingredients. Because bechamel is a base sauce, the flavours typically used are not strong, but there are several popular choices:

Halved or sliced onion.
Whole cloves.
Bay leaves.
Grated nutmeg.

Even if you’re going to convert your bechamel to a mornay with lots of shredded cheese, the addition of some of these flavours really does enhance the underlying flavour in a subtle but impactful way.

Thickening the sauce

Once the milk and the roux are fully combined the flour needs some time to do it’s work.

This is achieved by simmering over low heat while stirring regularly.

During this phase the starches in the flour are absorbing liquid. As they do this they swell and the sauce thickens. But this is not an instantaneous process – it takes a little time.

Again, there’s a lot of variation amongst the recipes in terms of the time they allow for their sauce to thicken:

Eight of the authors allow their sauce to simmer for 5 minutes or less.
Two give it 5 to 10 minutes.
Another five authors allow between 10 and 20 minutes.
And Faith from The Kitchn simply advises cooking until thickened.

Difficult to know how long it should take from these recipes!

Ultimately Faith’s guidance is the right advice. Every bechamel sauce will take a different amount of time to thicken because of variables like the heat of your stove, the ratio of roux to milk you used, the thickness of your pan and more.

I typically find it takes between 10 and 15 minutes to thicken my bechamel. But I tend to be conservative on the heat, especially if I’ve got a glass of red in my hand.

Closeup of a steel pot full of creamy bechamel sauce with a whisk in it.

Making a creamy, lump-free bechamel sauce

There are a few tips that will help ensure your bechamel turns out smooth and creamy every time:

For your roux, make sure you have at least as much butter as flour (by weight).
When making your roux, let a bit of the water bubble off your butter before you add the flour. Alternative, try clarified butter or oil.
Stir, stir, stir.
With the heat low, add the milk gradually, in small amounts initially.
Stir, stir, stir!

Jokes aside, stirring constantly with a whisk really is the key to keeping your bechamel lump-free. That and good temperature control (meaning don’t rush it with too much heat).

Taking your bechamel sauce to the next level

There are a number of great recipes here for a quick and easy bechamel. But if you’re looking to go a step further to a really flavoursome white sauce, there are a couple of key things you can do:

Cook your roux a little longer. Even if you can’t identify the raw flour taste, you will almost certainly notice the difference when it’s gone.
Infuse some flavours into your milk. Nutmeg is a great starting point, but combined with onion, cloves and bay leaves, you’ll find the difference is subtle but remarkable.

Both of these suggestions take more time, but they will change your view of a white sauce from a bland filler to a beautiful sauce in it’s own right.

Perfect for your next mac and cheese. Or even better, a lasagna with bechamel sauce or my Inside Out Lasagne!