Creamy Potato Soup

OK so it's getting cold in the UK now, so that means soup season is upon us. This is perfect to warm you up on a cold day.

Serves 4

2 leeks sliced
2 onions roughly chopped small
2 potatoes peeled and diced
50g butter
800ml vegetable stock 
200ml milk
Salt and pepper

1)In a large saucepan, gently melt the butter, then add the leeks, onions and potatoes, stirring them all round with a wooden spoon so they get a nice coating of butter. 
2)Season with salt and pepper, then cover and let the vegetables sweat over a very low heat for about 15 minutes.
3)After that, add the stock and milk, bring to simmering point, cover and let the soup bubble very gently for a further 20 minutes or until the vegetables are soft 
4)Put the whole lot into a blender – leave it to cool a little first – and blend to a purée.
5)return the soup to the saucepan and reheat gently, tasting to check the seasoning then serve!