Wash the apples and cut into pieces with the core. The core has to be cooked too, so that the pectin is retained due to its gelling ability. Cook with water until soft, then press the fruit pulp through a sieve or cloth. Bring the juice with the preserving sugar and the sliced vanilla pods to the boil while stirring and let it simmer for about four minutes. Remove the vanilla pods and stir in the juniper schnapps.
Pour the jelly hot into jars, close immediately and turn upside down for five minutes.