Yum! I love being able to take my time with this and let the onions braise in the oven for a few hours...but the quick and easy version is almost as good :)
3 large yellow onions, sliced
3 cloves garlic, minced
2 Tbsp. butter or margarine
1 Tbsp. Worcestershire sauce
1/4 tsp. black pepper
1/8 tsp. salt
4 cups beef broth
2 cups chicken broth
1/8 tsp. thyme
4 slices crusty bread (I sliced mine from a leftover French loaf I had)
4 tsp. softened butter or margarine
8 slices cheese (Swiss is traditional, Gruyere is a splurge...we usually go with plain mozzarella since I always have it on hand)
1. In a large stock pot over medium heat, combine butter and Worcestershire and heat until butter is melted. Stir in onions and garlic, and season with salt and pepper. Cook onions, stirring frequently, until soft and caramelized, about 20 minutes.
2. Increase heat to high, add broths and thyme, and bring to a boil. Reduce heat and simmer at least 30 minutes (or up to an hour).
3. Preheat your oven's broiler on the low setting. Place the bread slices on a baking sheet. Spread each slice with 1 tsp. butter and sprinkle with garlic salt. Broil until slightly crispy and light brown, about 2-3 minutes.
4. To finish: Ladle soup into 4 oven-proof bowls. Top soup with a slice of bread and 2 slices of cheese. Broil on low until cheese is melted and bubbly, about 3-4 minutes.