Preparation time: 10 minutes
Cooking time: Under 30 minutes

1. Cook the onions in butter and oil over medium heat until lightly colored. Sprinkle with flour, mix well and cook for a few moments.
2. Add the white wine. Reduce and add chicken broth, salt, pepper, the bouquet garni and garlic. 
3. Bring to a boil and simmer for 1 hour over low heat. Meanwhile, slice the bread thinly and dry briefly in the oven; remove. 
4. Combine the egg yolks and Madeira. 
5. When the soup is ready, remove the bouquet garni. Add the egg yolks and mix well. 
6. Ladle the soup into bowls. Place a few croutons on top and cover with gruyere. Place the bowls in a pan of hot water in a preheated 210° C (425° F) oven and cook for 10 minutes until the tops are browned and bubbly.

Variation MS

I add a piece of beef (such as blade) and simmer over low heat for 3-4 hours, doubling the quantity of water. Add more water along the way if necessary. The broth is delicious and concentrated enough that you don't need to add the egg yolks - perfect if you're watching your cholesterol.