Ingredients:
- 1 1/2 pounds ground beef
- 1 cup breadcrumbs
- 1/2 cup milk
- 2 large onions, thinly sliced
- 2 cloves garlic, minced
- 1 egg, beaten
- 2 tablespoons Worcestershire sauce
- 1 tablespoon Dijon mustard
- 1 teaspoon dried thyme
- 1/2 teaspoon salt
- 1/2 teaspoon black pepper
- 2 tablespoons butter
- 1/4 cup beef broth
- 1 cup shredded Gruyère or Swiss cheese
