3 tablespoons olive oil
2 large Vidalia onions, sliced
1/2 teaspoon kosher salt
1/2 teaspoon freshly ground black pepper
1 teaspoon fresh thyme leaves
4 cups beef broth
4 slices ciabatta bread, cubed
4 ounces sliced fontina cheese
Special equipment: 4 (1 1/2-cup) ovenproof ramekins