3 tablespoons butter
6 onions, thinly sliced
1/2 teaspoon salt
1 1/2 cups white wine
3 1/2 cups chicken broth
1/4 teaspoon ground white pepper
1/4 teaspoon ground nutmeg
2 cups shredded Gruyere cheese
In a medium saucepan over medium heat, cook butter until foamy. Stir in onions and cook a couple of minutes, then reduce heat, stir in salt, cover and cook very slowly until very tender, 60 minutes.
Transfer onions and their caramel to a larger pot and place it over medium heat. Pour in the wine and bring to a boil. Stir in chicken broth, pepper and nutmeg and simmer gently, uncovered, 15 minutes.
Stir in shredded cheese until melted (cheese will remain a little stringy). Serve.