Ingredients
2 Tbsp olive oil, plus more to brush toasts
2 Tbsp unsalted butter
3 lbs yellow onions, about 6 large onions, halved, peeled and thinly sliced with the grain
1/2 tsp granulated sugar
2 garlic cloves, minced
1/2 cup dry sherry wine, or use dry vermouth or dry white wine
8 cups beef stock, or broth
1 bay leaf
3 sprigs fresh thyme, plus more to garnish (or 1/4 tsp dried thyme)
1 1/2 tsp salt, or to taste, divided
1/2 tsp black pepper, or to taste
12 slices baguette
8 oz gruyere cheese, 1 1/2 cups shredded, divided