Crumble the lady fingers and sprinkle with rum. Drain the mandarins in a sieve, collecting the juice. Put 8 mandarin slices aside for the garnish. Stir yoghurt, 2 tablespoons tangerine juice, vanilla sugar and sugar until smooth.
Whip the cream until stiff and carefully fold into the yoghurt. Fill mandarins, cream yoghurt, sponge crumbs and finally a layer of cream yoghurt into the glasses. Decorate with brittle, mandarin wedges and mint.