The all-in-one method really is so much easier and (I hesitate to say this) foolproof, which is why I'm amazed that everyone isn't doing it. The secret is to keep whisking - gently is fine but be sure to get into the edge of the pan to avoid any sneaky lumps forming. Perfect for lasagne, macaroni cheese and cauliflower cheese ♡
Add the milk, cubed butter and plain flour to a medium saucepan.
Over medium heat whisk constantly using a balloon whisk until the butter melts and the sauce thickens, becoming smooth and creamy. This will take about 3 minutes.
Reduce the heat to low and cook for a further 2 minutes, whisking continuously.
Season with salt and pepper.
The secret to this method is to keep whisking - gently is fine but be sure to get into the edge of the pan to avoid any sneaky lumps forming. There's no 'technique' to this, just be thorough and consistent with your whisking - nothing more than that.
The contents of your pan may look horrific at the start but soon the flour mixes into the milk and the butter melts and then it's easier to see that you're on the way to success.
The sauce thickens quite a lot as it cools. The measurements in the recipe make quite a loose sauce (that's how I prefer it) adjust to less milk if you like it thicker.
You can make your white sauce in advance. I use a piece of cling film and lay it directly over the sauce (while it's still hot) to prevent a skin from forming. It will keep in the fridge for a couple of days.