Caramelize the onions, butter, olive oil, salt and pepper on low stirring about every 5 minutes at first, then towards the end when they pick up more color every 1-2 minutes until they are brown.
Deglaze the pan with the Worcestershire sauce and vinegar.
Add the rest of the ingredients (minus the cream and cheese) and simmer covered until potatoes are soft.
Take about half a cup of potatoes out and mash them until mashed potato consistency.
Stir back in the pot to thicken the broth.
Add cream and mix in.
Serve with a layer of cheese on top.
Torch this with a blowtorch or put it under the broiler in the oven. Make sure to use an oven safe dish.
