Place the chicken livers in a bowl with the red wine, garlic, chopped thyme and nutmeg. Leave to marinate in the refrigerator for 4 hours or overnight.
Lift the livers out of the marinade using a slotted spoon and set aside. Pour the marinade into a saucepan. Add the onion and cook over a low heat for 15 minutes, or until the onion is soft and the liquid has completely evaporated.
Meanwhile, put 1 tablespoon of hot water in a small bowl, sprinkle the gelatine over it, then stir briskly until dissolved. If the gelatine does not fully dissolve, stand the bowl in a saucepan of hot water and stir until it has dissolved.
Heat the butter in a non-stick frying pan and sauté the livers for 3 minutes over a moderate heat. Season. Cool slightly, then tip the livers and juices into a blender or food processor and purée until smooth. Add the onion and gelatine liquid. Blend again and check the seasoning.
Transfer the pâté to a small earthenware dish, cover and chill for at least 4 hours until firm. Garnish with thyme and serve with mini toasts or crackers.