Chicken Stroganoff

Name: Chicken Stroganoff
Ingredients: 1 tablespoon unsalted butter; 8 ounces cremini mushrooms, sliced; Kosher salt and freshly ground black pepper; 1 1/2 pounds boneless, skinless chicken breasts, cut into chunks; 1 tablespoon olive oil; 1 yellow onion, thinly sliced; 3 tablespoons all-purpose flour; 3 cups chicken broth; 1 tablespoon Worcestershire sauce; 1 packet French onion soup mix; 1/3 cup sour cream, plus more for serving; Cooked wide egg noodles, for serving; 3 tablespoons minced fresh chives