Melt butter and oil in heavy sauce pan over moderate heat
2
Stir in sliced onions (2 and 1/2 lbs) and cook slowly until tender - 10 - 12 minutes
3
add salt and sugar and increase heat to medium high - cook for around 25 minutes stirring frequently. Onions should get very dark in color.
4
Add flour and cook slowly - stiring constantly for 3 minutes
5
Remove from stove and whisk in 2 cups of warm stock
6
Return to stove and simmer
7
Add rest of stock, 1/4 cup brandy and wine
8
Simmer - loosely covered for 1 1/2 hours
9
brush bread cubes lightly with olive oil and brown under broiler - remove from broiler and turn cubes over and brush other side lightly with oil and return to broiler to brown.
10
When ready to serve, add bread cubes to top of soup bowl and cover with gruyere cheese - brown under broiler until cheese is melted. Serve immediately.