Grease a springform pan (26 cm Ø). Put the rusk into a freezer bag and crumble it finely with a dough roll. Melt butter, stir in 125 g sugar and add 5 tbsp. cold water. Mix with rusk
Spread the rusk crumbs in the form. Press on the bottom and 3-4 cm high on the edge of the tin. Cool for about 20 minutes.
Drain the mandarins. Beat the eggs, 175 g sugar, vanillin sugar and salt for about 5 minutes until fluffy. Mix quark, cream cheese, orange juice, orange and lime peel and flour. Stir into the egg mixture
Place mandarins, except 2-3, on the rusk base, spread cream cheese mixture on top. Bake in a hot oven (electric cooker: 150 °C/circulating air: 125 °C/gas: level 1) for approx. 30 minutes. Then bake at 175 °C (fan oven: 150 °C/gas: level 2) for about 45 minutes. If necessary, cover with parchment paper after approx. 30 minutes
Remove from the edge, cool down. Decorate with icing sugar, rest of mandarins, citrus slices
This way your cheesecake will not collapse after rising: after half the baking time, use a sharp knife to cut between the edge of the mould or short pastry and the cheese mass. Let the cake rest for 5 minutes and then continue baking