white onion soup

this is one of the most delicious soups there is: 
comfortingly simple, yet richly luxurious.
you can use brown onions for this, or, even better, the white-skinned ones that sometimes turn up in ethnic and italian stores.
don't, though, be tempted to use red: pink onion soup isn't as pretty as it sounds.

serves 4

50 g butter
500 g onions, peeled and finely sliced
leaves from 2 bushy sprigs of thyme
salt and black pepper
100 ml dry white wine
600 ml chicken stock
100 ml double cream

melt the butter over a gentle heat.
add the onions, thyme and 1/2 tsp salt.
mix so the onions are coated in butter.
cover the pan and sweat for 30 minutes, stirring a few times, until the onions are soft and buttery, but not coloured.
add the wine, turn up the heat and bubble for 5 minutes.
pour in the stock and simmer gently for 20 minutes.
blitz the soup with a stick blender until perfectly smooth.
season, stir in the cream and gently reheat without boiling.
finish with a few grinds of black pepper.