Defrost the puff pastry. Peel oranges so that the white skin is completely removed. Cut out the fillets between the parting skins and collect the juice. Mix juice, liqueur and sugar. Marinate the fillets for about 20 minutes.
Place the slices of dough on top of each other. Roll out slightly (approx. 12 x 22 cm) and cut out 4 oval pieces (approx. 5 x 10 cm). Place on a baking tray lined with baking paper and spread with condensed milk. Bake in a preheated oven (electric cooker: 200 °C / convection oven: 175 °C / gas: level 3) for about 10 minutes until golden brown. Take out, let cool down
Whip cream until stiff, add vanilla sugar. Cut the puff pastry pieces horizontally. Cover the lower halves with a few orange fillets each
Spray cream onto the oranges using a piping bag with a star-shaped spout. Put the lid on top. Dust with icing sugar. Arrange cream slices, rest of oranges and marinade