YIELD: 6 servings
TOTAL TIME: 1 1/2 hr
Cook onions, thyme, bay leaves, and salt in butter in a heavy pot over medium heat, uncovered, stirring frequently. Cook until the onions are soft and develop a deep golden brown color, about 45 minutes. Add flour and cook, stirring, 1 minute. Add in the wine and cook, stirring for 2 minutes. Stir in broth, water, and pepper and simmer, uncovered, stirring occasionally, 30 minutes.
Toast slices of baguette in 350 degree oven, on a large baking sheet, turning over once for about 15 minutes.
Divide soup among crocks or heat proof mugs, then float a crouton in each. Top each with slices of cheese and sprinkle with Parmigiano. Broil 4 to 5 inches from heat until cheese is melted and bubbly, 1 to 2 minutes.