Ingredients
Method
- Melt butter, add onions, and cook low and slow until deeply caramelized for about 30 minutes.
- Stir in flour, mustard powder, salt, pepper, and thyme.
- Gradually add broth, bay leaves, white wine, salt, and pepper; simmer 15–20 minutes.
- Ladle into bowls, top with bread and cheese, then broil until bubbly and golden.