Creamy Chicken Soup With Caramelized Onions

Ingredients

• boneless, skinless chicken breast , patted dry
• teaspoons fine salt, plus more as needed
• freshly cracked black pepper
• tablespoons olive oil
• small yellow onion, diced
• dry white wine, such as sauvignon blanc, divided
• chicken or vegetable broth, preferably no-salt-added
• large Yukon Gold potato , peeled and diced
• heavy cream
• shredded Gruyère cheese
• Chopped fresh chives, for garnish