Source: Molly

3 pounds onions. Peeled, halved, thin sliced. Dutch oven with 6-8 tbs butter. Onions in. Cook 5 mins covered. Uncover. Caramelize onions 1 hour, stirring now and then. Add 2 tbs flour. Mix and cook 1 min. 1 cup dry white wine. 1-2 oz sherry. Stir 3 mins. 4 cups beef stock. Salt and pepper. Done.

Toast. Cheese. Broil.