4 pounds onions (sweet onions work nicely)
3 T butter
1 tsp. salt
2 c. white wine
3-4 c. vegetable stock
1 c. apple cider (or more if you prefer a bit sweeter taste)
1 tsp. thyme
1 tsp. parsley
1 bay leaf
8 slices french bread
1 cup Fontina or Gruyere cheese, grated (Asiago or Mozzerella will do in a pinch)
Peel and slice the onions into thin wedges. Place a large skillet over medium heat and add butter. Once butter has melted add a layer of onions and sprinkle with a little salt. Repeat layering onions and salt until all onions are in the skillet. Cook for 15 to 20 minutes without stirring. After that, stir occasionally until onions are very well browned and reduced, 45 minutes to 1 hour. Do not worry about burning.
Add wine and turn heat to high, reducing the wine to a syrup consistency. Add broth, cider and herbs. Reduce heat and simmer 15 to 20 minutes.
Place oven rack in top 1/3 of oven and heat broiler. Place the slices of bread on a baking sheet and place under broiler for 1-2 minutes, until toasted.
Season soup mixture with salt and pepper; remove bay leaf and ladle soup into broiler-safe crocks. Place bread, toasted side down, on top of soup and top with grated cheese. Broil until cheese is bubbly and golden, 1 to 2 minutes.