Peel the oranges with a knife including the white skin and cut into finger-thick slices. Catch the juice in the process. Then marinate the fruit slices in liqueur. Soak gelatin. Mix the quark with the sugar until smooth. Line a bowl (capacity approx. 1 liter) with cling film, then place the orange slices next to each other up to the edge. Cut the remaining orange slices into small pieces and fold into the quark cream. Dissolve the gelatine dripping wet over low heat and stir with the collected juice. Stir into the cream, then pour the cream into the bowl and chill. When the cream starts to gel, fold in the whipped cream. Chill for at least 3 hours. Then turn the charlotte on a plate and garnish with chocolate decor, cream and orange pieces and sprinkle with the chopped pistachios.