In a stock pot, or dutch oven over medium heat, heat oil and butter. Add onions and cook for about 15 minutes. Stir frequently as onions will want to stick the bottom of the pan. The onions will become caramel colored.
Reduce the heat to medium low, cover the pot, and continue cooking for another 20 minutes or so, stirring occasionally. The onions will continue to darken and turn golden brown.
Add sherry to pot, increase the heat to high and cook until sherry evaporates, about two minutes.
Stir in Worcestershire Sauce, Kitchen Bouquet, beef stock, thyme, salt and pepper. Simmer, covered for 20 minutes.
Preheat the oven to 350 degrees
While the soup is simmering on the stove, slice the bread. Lightly butter each side (I used a butter flavored spray) Add the buttered, sliced bread to a baking sheet.
Bake in oven on 350 degrees for about 10-15 minutes. Until bread is golden brown and toasted, turning it over once, half way through. Cool.
Ladle soup into oven safe crocks or bowls, arranged on a baking sheet. Add 2-3 pieces of bread, top with cheese, and place in oven, about 6" beneath broiler, set to high broil and broil for about 2-5 minutes. Tops will become brown and bubbly.
The bowls will be HOT when they come out of the oven, so be careful. Serve immediately and enjoy!