How to Make a Smooth Cheese Sauce Without Lumps (Even If You're Nervous)
A cheese sauce can feel like one of those things you either can do or you can't. In our kitchen we call it “quite a scary sauce to make”, and Mac is a trained chef. The good news is that smooth comes down to three simple habits: gentle heat, a little milk at a time, and not rushing.
This is the method from our loaded chips recipe, where the sauce is made while the wedges roast. It works for any cheese sauce, whether it goes over chips, jacket potatoes, pasta or a lasagne topping.
Start with a roux
A roux is just butter and flour cooked together. Use equal amounts of each. Melt the butter, add the flour and cook for about two minutes, stirring, without letting it brown. This cooks out the raw flour taste.
There is not much to see. It will not change colour much, but you may notice it starts to stick a little more to the pan instead of looking glossy.
Keep the heat gentle
This is the one that catches people out. Mac’s advice: “You don’t want the heat too intense, because the natural sugars in the milk, as well as the starch, will burn your pan.” A medium-low heat and a stirring spoon are all you need.
Add the milk a little at a time
Add the milk in small splashes and let each one be taken up by the roux before you add the next. In the video Mac adds cold milk to a hot roux, a little at a time, and keeps stirring. Some cooks warm the milk first, which also works. The point either way is to go slowly. Adding milk too quickly is the most common cause of lumps.
“That way, it keeps it smooth. You don’t get lumps.”
Get the thickness right
For a sauce to drizzle over loaded chips, you want it thick enough to draw a line across the back of your spoon without it running back together, but still creamy enough to pour. Mac added a little more milk than the recipe said, because the right amount depends on the flour you use. Different flours hold different amounts of starch, so go by how the sauce looks and feels rather than the exact number.
Add the mustard and cheese
Stir in a little English mustard (Dijon works too) and then the cheese. Many cooks take the pan off the heat before stirring in the cheese. If the cheese gets too hot, the sauce can turn grainy or oily. Taste before you add salt, because cheese is already salty.
Lumpy? Here’s how to fix it
- Lumps at the end: Mac’s fix is a hand blender: “If you do get lumps at the end, you can always use a hand blender just to blitz it to bring it back to consistency.” Whisking hard or pushing the sauce through a sieve also works.
- Tastes floury: The roux needed a little longer. Next time, give it a full two minutes before the milk goes in.
- Too thick: Whisk in a splash of milk. Remember it thickens as it cools.
- Too thin: Simmer it gently for a few more minutes.
- Catching on the bottom: Turn the heat down and stir right into the corners. A heavy-based pan helps.
It gets easier
The more you make it, the less of a worry it becomes. Once you know what you are looking for, it becomes a case of touch and feel. Mac says it best: “The more you do it and you try it… as long as you’re taking your time and the heat’s not too much, you’ll get there, no problem at all.”
If you have never made one, a good time to practise is while something else is cooking. In our loaded chips recipe, the wedges take about 25 minutes in the oven, which is plenty of time to take it slowly.
Questions people ask
Why is my cheese sauce lumpy?
Usually the milk went in too fast, or it was not stirred enough as it went in. Add it a little at a time next time, and blend or sieve the sauce if you need to rescue it.
Why is my cheese sauce grainy or oily?
The heat was probably too high, or the cheese got too hot. Cook gently and add the cheese off the heat.
What can I use cheese sauce for?
Pour it over chips and wedges, jacket potatoes, pasta bakes, or use it as a lasagne topping.
See it in action
Our Loaded Ultimate Chips recipe has the full ingredients and the video. We also wrote about why a proper cheese sauce beats melted cheese.
