French Onion Soup

1. Cook onions, thyme, bay leaves, and salt in butter in a 4- to 5-quart heavy pot over moderate heat, uncovered, stirring frequently, until onions are very soft and deep golden brown, about 45 minutes. Add flour and cook, stirring, 1 minute. Stir in wine and cook, stirring, 2 minutes. Stir in broth, water, and pepper and simmer, uncovered, stirring occasionally, 30 minutes.
2. While soup simmers, put oven rack in middle position and preheat oven to 350 degrees F.
3. Arrange bread in 1 layer on a large baking sheet and toast, turning over once, until completely dry, about 15 minutes.
4. Remove croutes from oven and preheat broiler. Put crocks in a shallow baking pan.
5. Discard bay leaves and thyme from soup and divide soup among crocks, then float a croute in each. Slice enough Gruyere (about 6 ounces total) with cheese plane to cover tops of crocks, allowing ends of cheese to hang over rims of crocks, then sprinkle with Parmigiano-Reggiano.
6. Broil 4 to 5 inches from heat until cheese is melted and bubbly, 1 to 2 minutes.
7. Soups and croutes can be made 3 days ahead (but do not add croutes and cheese to soup); cool completely, uncovered, then chill soup, covered, and keep croutes in an airtight container at room temperature. Reheat soup before proceeding with recipe.

Yield: 6 servings