Melt the butter in a large frying over medium heat. Stir in the apple and onion; cook and stir until the onion has softened and turned translucent, about 10 minutes. Stir in the flour, chicken stock and extra light cream, cooking until the sauce has thickened, about 5 minutes. Season with curry powder, salt, ground ginger and cayenne pepper. Add the chicken then cover and cook until the chicken is longer pink in the centre, about 10 minutes.