Cream the quark with and cherry juice, cherry liqueur, lemon juice and sugar until smooth. Whip the cream until stiff and gently fold into the quark mixture.
Chop the chocolate and melt slowly in a bowl placed over a bowl of simmering water. Brush into the tartlets and let cool.
Spoon cherry cream into a piping bag fitted with a star tip and fill the tartlets. Garnish with candied cherries and sliced nougat bars and serve.