Make juice from the quinces (with the help of an electric juicer). From the 3 kilos of quince I get exactly 2 liters of quince juice.
Heat the quince juice together with the remaining ingredients in a large saucepan, stirring constantly, and bring to the boil briefly. Let the juice cool down and mix with the bottle of rum. Fill into beautiful bottles (quantities for 6 x 0.5 liter bottles) and leave to rest for at least 4 weeks. But it tastes delicious even after two days.
Tip for cheap bottles: I buy beer in swing top bottles with clear glass, force my husband to drink them empty and replace the label with my own.