Creamy French Onion Soup In Bread Bowls

Bahan-bahan (6 porsi)

• 6 tablespoons salted butter
• 4 -5 medium yellow onions, thinly sliced
• 1/2 cup apple cider
• 1 cup dry white wine ((such as Pinot Grigio) )
• 3 cloves garlic, chopped
• 2 tablespoons fresh thyme leaves
• 2 tablespoons chopped fresh sage
• 6 -8 cups beef or vegetable broth ((use vegetable broth if vegetarian))
• 2 teaspoons Worcestershire sauce ((omit if vegetarian))
• 1 parmesan rind
• kosher salt and black pepper
• 1 cup heavy cream or whole milk
• 4 -6 sourdough bread bowls, bowls hallowed out, reserve the tops ((optional))
• 8 to 12 slices Gruyère cheese