The onion soup can be made a day or 2 ahead of time, reheated and gratinéed before serving.
Ingredients
4 lg. Yellow Onions, thinly sliced (about 8 c.)
4 Tbsp. (1/2 stick) Butter
1 tsp. Salt
¼ c. Cognac or Brandy
3 sprigs Thyme
Black Pepper
6 c. Warm Beef Stock, preferably homemade- see notes
1 c. Aged Gruyere, grated
12 slices Baguette, toasted
Instructions
Heat butter in a heavy-bottomed soup pot over medium-low heat. Add onions and salt. Slowly caramelize, stirring occasionally, until dark and sweet, 1-1½ hours.
Add Cognac and scrape up any onion bits that might be stuck to the bottom of the pot. Add thyme, a generous amount of black pepper, and warm beef stock. Bring to almost boil, then reduce heat to simmer. Simmer for about 15 minutes until the flavors have melded. Remove thyme stem and adjust seasonings, if necessary.
Ladle soup into 4 ovenproof bowls set on a baking sheet. Top each bowl with 3 slices of toasted baguette and ¼ c. of cheese. Place under broiler for 2-4 minutes, watching carefully, until cheese is melted and the bread is golden around the edges.
Notes
Homemade stock is easy to make, requires very little hands-on time, and will greatly improve the flavor of this soup. To make beef stock, roast 3# beef soup bones with roughly chopped onions(2), celery stalks(2), carrots(2) in a very hot oven for 30 minutes. Place roasted bones and vegetables in a stock pot and cover with about a gallon of water. Add 1 tsp. salt, 10 black peppercorns, 2 cloves garlic, 5 whole cloves, handful of parsley, 3 bay leaves. Bring to an almost boil then reduce heat and simmer for 2-3 hours. Strain and it is ready to be used or frozen for future use.
Recipe by strawberryplum at http://www.strawberryplum.com/french-onion-soup-soupe-a-loignon-gratinee/