Rub the quinces, wash off if necessary. Cut out the middle with a sturdy apple cutter or a sharp knife. Sprinkle the outside of the quince with rock sugar. Place about 1 teaspoon of butter, 1 teaspoon of rock sugar and 1/2 sliced vanilla pod each in the middle of the quince.
Wrap the quinces individually in aluminum foil and place on a baking sheet. Roast in the oven preheated to 160 ° C, fan oven 140 ° C, gas mark 2 for 60-80 minutes until soft.