Cut the tops and bottoms off the leeks (make sure they are clean) then slice them into inch chunks.

Melt the butter in a large sauce pan, add the leeks and onions and soften them over a gentle heat for 5 minutes.

Meanwhile mix the stock cube with the water then add it to the onions and leeks, bring to the boil.

Peel the slice the potatoes in half wash, (stir every 5) them and then add them to the stock allow to simmer for 20 minutes.

Add the milk and return to the boil.

Season to taste.

Blend with a hand blender or food processor untill smooth.

Serve in a bowl with some fresh chopped parsley or croutons.