Peel 2 oranges so that the white skin is completely removed. Cut both oranges into thin slices. Cut 1 orange in half and squeeze the juice (makes about 6 tablespoons of juice). Place 90 g cantuccini in a bowl. Mix 4 tablespoons of orange juice with the liqueur. Dribble half of it onto the cantuccini, cover with half of the orange slices. Sift the icing sugar, mix with cream stabilizer.
Whip the mascarpone briefly with the whisk of the hand mixer, gradually adding yoghurt and icing sugar mixture. Season to taste with 1-2 tablespoons of orange juice. Fill half of the cream onto the orange slices in the bowl. Layer 90 g cantuccini on top, drizzle with the remaining juice-liqueur mixture and cover the remaining orange slices. Spread the rest of the cream on top in waves. Chill the orange tiramisu for at least 1 hour. Dust with cocoa before serving