Whip the cream in a cold baking bowl until stiff (best done by hand with a whisk) and refrigerate until needed. Soak gelatine in a little cold water. Beat the egg yolks and sugar with a hand mixer until creamy. Flavor with the orange liqueur, add the quark and the pulp of the vanilla pod. Melt the gelatine with a few drops of water in a small pan at a low temperature, then add it to the mixture and fold in the whipped cream. Pour the puree into a suitable bowl and leave to cool for at least 3 hours. Remove the peel from the oranges and cut the white skin into small pieces. Using a pointed kitchen knife, separate the orange fillets along the partitions on the left and right sides, collecting the juice.
Caramelize the sugar in a small pan at moderate temperature until golden brown, extinguish with the collected orange juice (about 0, 1 liter) and make until the sugar is completely dissolved. Add orange liqueur, strain the sauce through a sieve into a small baking dish. Steep the orange fillets in this sauce until completely cool.
To serve, use a tablespoon to make dumplings from the puree, arrange with the orange fillets and sauce. Decorate with lemon balm.