Trim excess fat from chops, sautee chops in hot butter until golden brown, remove from pan. Peel and chop onion and apple finely, add to pan, sautee until onion is transparent. Remove from panand drain. Add flour, curry powder, salt and pepper and mustard to pan, cook 3 minutes. Dissolve chicken stock cubes in boiling water, add worcestershire sauce, add to flour mixture, stirring continually. Stir until sauce boils and thickens, reduce heat, simmer 3 minutes. Return chops, onion and apple to sauce, cover, simmer 1 hour or until chops are tender.