Method 1. Melt the butter in a large, heavy frying pan over moderately high heat. Add the onion and apple, and cook for 5 minutes, until tender.
Blend in the flour, add the chicken stock and cream, and cook, stirring continuously, until the sauce has thickened - about 10 minutes.
Stir in salt, curry powder, cayenne pepper and ginger. Add the chicken / turkey and simmer, covered, over very low heat for 10 minutes.