Knead the muesli with 75 g sugar and the butter.
Press the mixture onto the base of the greased springform pan. Chill.
Drain the mandarins, catching the juice.
Mix the cream cheese smoothly with the quark, yoghurt and lemon juice.
Add sufficient water to the mandarin juice from the tins to make 150 ml.
Put the juice into a pan with the cake glaze powder and 100 g sugar, mix and bring to the boil.
Remove from the heat, cool slightly, then fold into the cream cheese mixture.
Fold the drained mandarins into the mixture and spread smoothly on the cake base. Chill for 3 hours.
Peel the fresh mandarins, removing all the white skin and pith, slice across and lay on top of the cream.
Warm the marmalade, strain through a sieve and brush the top of the cake. Sprinkle with a little muesli.