Chicken Stuffed with Walnuts, Apples and Brie

Ingredients

• chopped onion
  1/4 cup
• butter

  divided
  3 tablespoons
• chopped peeled apple
  1/2 cup
• chopped walnuts

  toasted
  2 tablespoons
• dried rosemary

  crushed
  1/8 teaspoon
• plus 1/4 teaspoon salt

  divided
  1 Dash
• plus 1/4 teaspoon pepper

  divided
  1 Dash
• boneless skinless chicken breast halves (6 ounces each)
  2 unit
• garlic powder
  1/8 teaspoon
• Brie cheese

  cubed
  2 ounces
• cider vinegar
  1/4 cup
• unsweetened apple juice

  divided
  3/4 cup
• cornstarch
  1-1/2 teaspoons