Soak the gelatine in cold water for 5 minutes, then squeeze out. Heat gently in 1 tablespoon of wine until it dissolves. Mix the elderflower syrup with the rest of the wine, stir into the dissolved gelatine, chill.
Whip the cream. As soon as the elderberry and wine mixture begins to gel, fold in the cream and yoghurt and chill for about 2 hours.