Cut the oranges crosswise into halves of the same size and carefully squeeze out the juice. However, the shell must not be damaged in the process!
Beat the orange juice, sugar and egg yolk in a water bath for about 5 minutes with a whisk. Soak the gelatine cold according to the instructions on the packet, then squeeze out and dissolve. Add the gelatine to the orange juice mixture and stir everything well. Whip the cream with vanilla sugar until stiff and add half of it to the cold, not yet hardened cream.
Carefully scrape out the orange halves. Then pour in the cream and let it solidify.
Serve garnished with the remaining cream and chocolate flakes.