Preheat oven to 200°C. Season chicken. Heat oil in ovenproof frypan over medium heat. Cook chicken skin-side down for 2-3 minutes until golden. Cook for 1 minute on other side. Place pan in oven for 8 minutes. Sprinkle chicken with sugar and add peaches, wine, stock and vanilla pods and seeds to pan. Return pan to oven for 8 minutes or until chicken is cooked through, basting twice with pan juices. Remove chicken and peaches from pan and keep warm. Return pan to stove and simmer cooking juices over medium heat for 2-3 minutes to reduce. Serve chicken with peaches and vanilla sauce. Garnish with watercress.