Meanwhile, slowly saute the leek in some olive oil in a saucepan over a medium heat until slightly carmelized. Add stock and simmer lightly. Remove parsnips and fennel from roasting pan and add to the soup. Remove garlic cloves from the pan, snip off one end of each clove and squeeze the garlic into the soup. Heat it up.

Whizz it all down with a hand held blender or in batches in a food processor. Add lots of freshly ground black pepper.