Onion, Mushroom & Hobgoblin Soup (James)

I initially came up with the idea for this after reading this recipe:
http://allrecipes.co.uk/recipe/4171/caramelised-onion-and-ale-soup-with-beef-strips.aspx

I've modified it but removing the beef strips (nice, but unnecessary for a simple dish).

Cooking time: about 45minutes
Serves: This makes about 2 bowls.

Ingredients:
2 whole red onions
3 garlic cloves
between a quarter of a pint and half a pint of Hobgoblin ale (or whatever is your favourite, darker, richer ales work better)
3 heaped teaspoons of brown sugar
a big dollop of butter (about a mega-heaped tablespoon)
tablespoon of cooking oil (extra virgin oil if you will)
700mls of boiling water
2 oxo cubes (beef or veg can work, I prefer beef)
cracked pepper
1 teaspoon of salt
generous handful of mushrooms

Method:
Get a fairly big saucepan and heat the butter and oil until the butter melts through and is sizzling
Slice the onions finely then add them along with the brown sugar, stirring through the oil & butter
Leave to cook for around 10 minutes, stirring occasionally
Slice the mushrooms and add them after 10 minutes and stir through
Cook for another 5 minutes or until the onions have caramelised
Add the Ale
Sniff the mixture, and stir it thoroughly
Bring it to the boil and and cook for 5 minutes or so
Whilst the ale is cooking in, prepare the 2 oxo cubes ground into the 700ml of boiling water
Add the beef stock, bring to the boil
Simmer for another 15minutes
Once the mixture begins to reduce, it's ready to serve
Reduce further if preferred