A good lasagne white sauce is just butter, flour and milk, whisked into a silky béchamel in about 15 minutes. This recipe gives you a foolproof, lump-free sauce, then shows how to thicken or thin it for dried or fresh pasta and how to adapt it for vegetarian lasagne.
Prep: 5 minutes · Cook: 10 minutes · Serves: 4 (enough for one family-size lasagne) · Dietary: Vegetarian (if using vegetarian hard cheese)
Lasagne white sauce ingredients
- 50g unsalted butter
- 50g plain flour
- 500ml whole milk, warm
- Salt and black or white pepper, to taste
- A pinch of grated nutmeg
- Optional: 50g grated Parmesan or Cheddar
This recipe yields ~500ml (ideal for a 4-layer 20x20cm dish). For a larger 6-person baking dish or extra-cheesy lasagne, scale up by 1.5x (75g butter, 75g flour, 750ml milk).
You will also need a heavy-based saucepan, a balloon whisk and a wooden spoon.
How to make lasagne white sauce
- Melt the butter. Melt the butter in a heavy-based pan over medium-low heat until it foams gently. Don’t let it brown.
- Cook the roux. Add the flour and stir continuously to cook for 1–2 minutes until its bubbling and pale golden and you have a smooth paste. This cooks out the raw flour taste.
- Add the warm milk gradually. Warm the milk in a separate pan or the microwave while the roux cooks. Pour it in a splash at a time, whisking constantly, and wait until each addition is absorbed before adding more. This is the step that prevents lumps.
- Simmer. Keep the pan over medium-low heat for 5 to 10 minutes, whisking now and then, until the sauce coats the back of a spoon and turns glossy.
- Season. Take the pan off the heat and stir in salt, pepper and a pinch of nutmeg. Stir in the cheese now if you’re using it.
- Use or store. Use it straight away, or press clingfilm onto the surface to stop a skin forming.
How thick should lasagne white sauce be?
The right thickness depends on your pasta and ragù. Dried sheets absorb liquid as they bake, so the sauce needs to be looser. Fresh pasta is already hydrated, so it needs a thicker sauce.
| Pasta | Milk (for 50g butter + 50g flour) | Consistency | Notes |
|---|---|---|---|
| Dried (no-cook) sheets | 600–650ml | Pourable, like double cream | Cover every edge of the pasta with sauce. Rest the assembled lasagne under foil for 30 minutes before baking. |
| Fresh egg pasta | 500ml | Thick, spreadable custard | Let the sauce cool slightly, then bake straight away. Fresh pasta needs less oven time. |
If the sauce thickens as it cools, loosen it with a splash of milk.
Traditional lasagne white sauce with ragù
For a classic Bolognese-style lasagne, keep the béchamel simple. Use only a small pinch of nutmeg, because a traditional ragù often contains some too. Skip the cheese in the sauce and sprinkle finely grated Parmigiano-Reggiano between the layers instead. British-style lasagne often uses a cheesy white sauce, which is fine if you prefer it.
Bake at 180°C fan (Gas 6) for 30 to 40 minutes until bubbling and golden, then rest for 10 minutes before slicing.
Vegetarian and vegan lasagne white sauce
Without meat, the white sauce has to carry more flavour.
- Add umami. Stir in a teaspoon of white miso, a splash of soy sauce or some grated vegetarian hard cheese at the end.
- Infuse the milk. Warm it with a bay leaf, a few peppercorns and a smashed garlic clove, steep for 10 minutes, then strain.
- Watch the moisture. Roast or sauté watery vegetables such as mushrooms, courgette and peppers first. Keep the sauce at the standard 500ml milk ratio.
- Go vegan. Use vegan block butter and unsweetened soy or oat milk (soy thickens best), and add 2 tablespoons of nutritional yeast for a cheesy note.
Traditional Parmesan contains animal rennet, so choose a vegetarian hard cheese if that matters to you.
Chef variations: Ramsay, Berry and Oliver
All three start from the same roux. They differ in ratios and finishing touches.
| Gordon Ramsay | Mary Berry | Jamie Oliver | |
|---|---|---|---|
| Fat and flour | 25g butter, 25g flour | 50g butter, 50g flour | 4 tbsp flour, olive oil |
| Milk | 300ml cold whole milk | 750ml hot milk | 1 litre semi-skimmed |
| Flavour | Nutmeg, 40–60g Cheddar | 2 tsp Dijon mustard, 50g Parmesan | Leeks, bay, nutmeg, 150g mature Cheddar (half in the sauce) |
| Method | Add milk in thirds, whisking | Whisk in hot milk gradually | Sweat leeks 30 minutes, add flour and milk, blend smooth |
| Result | Thick, quick cheese sauce | Looser, tangy, Parmesan-rich | Silky, sweet, hearty |
Pick Ramsay’s for speed, Berry’s for a looser sauce with more bite, or Oliver’s if you want extra vegetables hidden in the sauce.
Make ahead, store and fix
- Make ahead: Cover the surface with clingfilm and chill for up to 3 days. Reheat gently with a splash of milk, stirring until piping hot.
- Freeze: Cool completely, cover well and freeze. Thaw overnight in the fridge and whisk smooth.
- Lumpy sauce: Whisk hard off the heat, use an immersion blender, or push it through a sieve.
- Too thick or thin: Add a little warm milk to loosen it. Simmer a few minutes longer to thicken it.
No time? A 60-second no-cook alternative
Whisk together 400g crème fraîche (or ricotta), 50g grated Parmesan, 50ml milk, and a pinch of salt, pepper and nutmeg. Spread it between the layers as you would béchamel. It’s creamier and less classic, but works well in a quick lasagne.
Lasagne white sauce FAQs
What is lasagne white sauce called? Béchamel (besciamella in Italian): butter, flour and milk.
How do I stop lumps in lasagne white sauce? Add warm milk slowly, whisk constantly, and don’t walk away from the pan.
Which cheese is best? None is traditional. For a British-style cheese sauce (Mornay), stir mature Cheddar or Parmesan in off the heat.
Can I make it ahead? Yes. Cover the surface with clingfilm and keep it in the fridge for up to 3 days.
What else can I use béchamel for? Macaroni cheese, fish pie, potato gratin, creamy soups and seafood pies.