French Onion Soup

This is my all time favourite soup, I remember my first bowl of it at my uncles house when I was nine, it was superb; dark, rich and incredibly moreish.
It's a classic French dish of sheer simplicity in it's ingredients and techniques but requires care and attention to extract all the glorious flavour out of the humble onion, a vegetable often relegated to what you throw in the pan first.
The usual routine is to slowly saute the onions in a butter and oil, turning them from harsh, ridged eye waterers to a soft, golden, sticky pile of sweetness, true culinary alchemy.
However, Dom of Belleau Kitchen made a cracking version a few months back using a slow roasting method which managed to extract the wonder out of the onion without the faff of slicing and stirring beforehand, which I need to try. Either way, whichever technique you use, slowly is the key.

If I haven't convinced you yet, did I mention it's served with a slice of cheese on toast?

Ingredients
about a kilo of white onions, thinly sliced
40g butter
splash of oil
2 tsp of sugar
1.5 litres of beef stock
125ml of white wine.
Salt and Pepper
few slices of a crusty loaf
100g Gruyere cheese

Method
Melt the butter with the oil in a large saucepan and add the onions.
Over a low to medium heat, slowly fry the onions for at lest 20 minutes until they turn golden and sticky, add the sugar after 15 minutes to aid caramelisation.
Once nicely golden, add the beef stock, seasoning and wine to the pan, add a lid with a small gap and simmer very gently for at the very least an hour.
Slice the bread so it fits in your bowls, under a grill toast one side, turn over then add the cheese and toast again until melted. place on top of the soup in the bowl.
Serve and enjoy.