Peel the potatoes and thinly slice into half moons.

Thinly slice the onion and fry with butter in a saucepan until softened.

Add enough water so it more than covers the potatoes and then add the soup stock. When it comes to the boil, simmer until softened over low heat.

When it has softened, remove from the heat and let it cool. Put it in a blender, add a little milk, and switch it on!

Return to the pan, and add milk while heating it over medium heat until it reaches your desired degree of richness.

Adjust the taste with salt and pepper, pour into serving bowls, sprinkle parsley, and it's done!