How to make white sauce (béchamel)
Quick answer
Make a light roux from 25 g butter and 25 g flour for 1–2 minutes. Whisk in 400–500 ml warm milk a little at a time. Simmer 5–8 minutes, stirring, until the sauce is glossy and coats a spoon.
These steps assume
- Butter and flour are 1:1 by weight for a light roux.
- Milk is warmed before it is whisked in.
- The sauce is stirred regularly while simmering so the base does not scorch.
- The goal is a classic béchamel that coats a spoon.
This is what it should look like

Smooth pale béchamel coating the back of a spoon

Pale blond butter-flour paste ready for milk
What you need
- 25 g butter
- 25 g all-purpose flour
- 400–500 ml milk
- Small heavy-bottomed saucepan
- Whisk
- Salt, pepper and optional nutmeg
Step by step
1
Warm the milk in another pan or the microwave until hot to the touch — not boiling.
- Equipment: Second pan or microwave-safe jug.
- Heat: Low to medium heat.
- Time: 2–4 minutes.
- Looks like: Milk steams lightly; no skin if you stirred while heating.
- If it goes wrong: Milk boiled over — skim gently and use it still warm.
- Done when: The milk is warm and ready for the roux.
2
Melt the butter, sprinkle in the flour and whisk 1–2 minutes until smooth and light blond without browning.
- Equipment: Saucepan and whisk.
- Heat: Medium heat.
- Time: 1–2 minutes.
- Looks like: The paste smells lightly nutty, not of raw flour, and is still pale.
- If it goes wrong: Roux browned — for béchamel, start again; brown colour changes the flavour.
- Done when: Light roux ready for milk.
3
Whisk in the warm milk a little at a time until smooth. Add the rest and bring to a gentle boil while stirring.
- Equipment: Whisk.
- Heat: Medium heat.
- Time: 2–3 minutes.
- Looks like: No flour lumps; the sauce is even, still slightly thinner than finished.
- If it goes wrong: Lumps — take off heat, whisk or strain; add milk more slowly next time.
- Done when: Milk is incorporated without large lumps.
4
Simmer the sauce, stirring, until it coats a spoon. Season with salt, pepper and optional nutmeg.
- Equipment: Spoon.
- Heat: Low to medium — gentle simmer.
- Time: 5–8 minutes.
- Looks like: Sauce is glossy, smells of milk and butter, and leaves an even film on the spoon.
- If it goes wrong: Scorched base — change pans without scraping the burnt layer; keep heat lower next time.
- Done when: White sauce is smooth, glossy and seasoned.
If it doesn't turn out as expected
Lumps
milk too cold or added too fast; whisk off heat or strain.
Raw flour taste
undercooked; simmer a few more minutes while stirring.
Scorched base
heat too high or stirred too rarely.
Too thick or thin
adjust with warm milk or a longer simmer.
Food safety
Hot milk and sauce can scald. Keep the pan steady and stir away from your face.
When it's done: The sauce is smooth, glossy and white to cream-coloured with no lumps or raw flour taste.