Ingredients
4 large onions, thinly sliced
2 tablespoons butter
1 teaspoon sugar
2 quarts no-sodium beef broth
¼ cup sherry
2 fresh thyme sprigs
1½ teaspoons salt
Pepper, as per liking
Sliced bread (or use croutons)
8 ounces Gruyere cheese, sliced (Swiss cheese is a good alternative)
Preparation
In a 6-quart slow cooker, combine onions, butter, sugar, and salt. Cook on high for 7 hours or until onions are tender and have a rich brown hue.
Introduce beef broth, sherry, thyme, and season with pepper. Mix well, cover, and let it simmer on high for another hour.
At serving time, float slices of bread or croutons atop the soup. Crown with slices of Gruyere cheese.
Optional: For a more molten cheese layer, cook an additional 15 minutes.