This is my take on what is probably the ultimate winter-warmer classic. My variation is the stock. I always found beef stock such a fag to make and, frankly, it never seemed terribly successful (entirely down to me, of course). I do love eating duck and frequently made brown duck stock which I have found to be an excellent, suitably rich alternative which I commend to you.
Of course, since one can now buy very acceptable ready made stocks (for Heaven’s sake do NOT use cubes!), you could go ahead and use a good beef stock if you’d prefer a more original version of Soupe à l’Oignon Gratinée .
First, make the croûtons. Pre-heat the oven to 180°C/350°F/gas 4. Drizzle about two tablespoons of olive oil on a baking sheet, add two crushed cloves of garlic and spread it around mixing the garlic into the oil (use your hands). Place the slices of baguette on the oiled sheet turning them over to lightly coat both sides. Bake them in the oven for 20-25 minutes until crisp and crunchy.
Place a 3.5 litre flameproof casserole on high heat and melt the butter and 2 tablespoons of olive oil together. When hot, add the onions, 2 crushed cloves of garlic and the sugar, and fry turning everything occasionally until the onions begin to darken at the edges. (This should take 5 – 6 minures.) Reduce the heat to very low and continue cooking the onions very slowly for 30 minutes more. There should now be some nicely caramelized pan contents.
Pour in the stock and white wine, season, and increase the heat. While it is coming to the boil, stir with a wooden spoon scraping any caramelized residue from the pan bottom. Once at the boil, reduce the heat to very low again and leave it to cook very gently, uncovered, for about one hour. (All the above can be prepared in advance.)
When ready to serve, bring the soup back to simmering point and check for seasoning. Now is also the time to add the brandy if you wish.Serving this out of a tureen is apt to get very messy so I suggest you use individual soup bowls. Pre-heat the grill to high. Ladel the hot soup into the warmed soup bowls and top each with a croûton. Sprinkle the grated Gruyère over the croûtons and place the bowls under the grill until the cheese is golden and bubbling.
Warn your guests not to touch the bowls!