Cut each quince in half and scoop out the core with a melon baller or a knife, making sure to get all of the tough membrane-y bits in addition to the seeds. Cut each quince half lengthwise into 4 slices, then cut each slice crosswise into 1/2-inch cubes.

Put the quince, sugar, water, cinnamon stick, Allspice, cardamom, and vanilla paste in a pot; choose one that is large enough to allow at least 5 inches headspace as quince tends to float when it cooks. (If you want, you can cut out a circle of parchment to press on top to keep the quince submerged.) Bring to a boil on high heat, then lower to medium-low and maintain a constant simmer for then next 1 1/2 to 2 hours, stirring every so often.

If using the parchment, remove during the last half hour of cooking. The quince is done when it’s tender but not falling apart — similar in texture to a poached pear. Allow the preserves to cool to room temperature. Remove the cinnamon stick and cardamom pods, if using. Transfer the preserves to glass jars or plastic containers, cover, and store in the refrigerator for several months.