French Onion Soup (Soupe a l'oignon)

Thought I might kick off our French trip with a few French classics... Do try and use Gruyure cheese if you can, it does make a difference. This recipe was a adapted from SBS's Food Safari.

French Onion Soup (Soupe a l'oignon) Recipe

60g unsalted butter
4 -5 brown onions, peeled and finely sliced
2 sprigs thyme, stem removed
50g flour
2 litres water
1 glass white wine
100g French Gruyère cheese, ½ cut into cubes and ½ grated
1 baguette
Salt and pepper

Melt butter in a heavy saucepan, add onion then cook for 25 minutes until the onion is deep golden brown and beginning to caramelize. Stir from time to time.
Add flour and stir for 2 minutes.
Add water and wine and season with thyme,salt and pepper.
Add cubes of cheese, stir and bring to the boil.
Cover and simmer for 20- 25 minutes. Check seasoning.
Slice the baguette, sprinkle with the remaining cheese and grill until the cheese is melted.
Put the soup in a serving bowl and serve with the toasted baguette on top.