You can just forget about those small crocks for serving onion soup in-you're going to want a large bowl of this.
If you've never made your own, it might be a surprise just how different homemade French Onion soup is from the heavily salted clear broth with re-constituted onions most Americans are accustomed to. This soup isn't clear as it is thickened slightly with flour and contains a bit of butter.
A good slicer will make the five cups of thinly sliced onions a breeze, but a sharp knife will work as well. The soup needs quite a bit of time to cook-first softening and caramelising the onions and then simmering. I'd suggest saving yourself some effort by preparing the onions ahead of time (just cover them well so your fridge won't stink).
If you use bouillon rather than broth, omit the salt in the recipe. This recipe is based on the one in Mastering The Art Of French Cooking.
You Will Need:
1 1/2 lbs thinly sliced onions (about 5 cups)
3 tablespoons butter
1 tablespoon oil
1 teaspoon salt (if not using bouillon)
1/4 teaspoon sugar
3 tablespoons flour
2 quarts boiling broth (if using bouillon, use 1 quart bouillon (4 cubes) and 1 quart water)
1/2 cup vermouth (white)
salt and pepper to taste
3 tablespoons cognac
Hard toasted rounds of bread (dry in 325 oven 15 minutes each side on a baking sheet)
1-2 cups grated Parmesan cheese (or Swiss if you prefer)
In a large, heavy pot cook the onions in the butter and oil with the lid on for 15 minutes over low heat.
Uncover and raise heat to moderate. Add salt and sugar. Cook 30-40 minutes, stirring often until deeply browned.
Sprinkle on the flour and cook three minutes (use a wooden spoon-it helps scrape the bottom)
Off heat, add the boiling broth, vermouth and salt and pepper. Return to heat and simmer partly covered for 30-40 minutes, skimming the top occasionally.
Just before serving, stir in the cognac. Ladle the soup over the bread in a bowl and sprinkle with cheese.