Preheat oven to 200°C/Gas 6.

Cut a slice off the top of the garlic, enough to show the top of the cloves.

Place on a sheet of foil and drizzle with a little oil.

Bake for 45 minutes.

Remove from the oven and leave to cool slightly.

Fry the onion in some oil until they are soft.

Add the potatoes.

Add the stock.

Season with salt and pepper.

Simmer for 20 minutes, or until the potatoes are cooked through).

Squeeze the roasted garlic cloves into the soup.

Blitz the soup smooth.