Preheat the oven to 350 degrees F. Set the quince into a baking dish and pour a bit of water into the bottom. Bake the quince for 25-30 minutes, until they can be pierced with a dinner fork.

Remove the quince from the oven and let them cool. Once you're able to handle them without burning yourself, cut away any remnant of the blossom and then cut the quince into eighths.

Place the cubed fruit into a sturdy saucepan with a tight fitting lid and add the 3 cups of water. Set the covered pot on the stove over a medium-high heat and bring to a boil. Reduce the heat to medium-low and simmer the fruit until breaks down into a chunky sauce.

Fit a food mill with its finest screen and push the quince sauce through. Work the food mill until all you have left are seeds, skins, and core material in the top.

Rinse out the saucepan to remove any scummy residue and return the puree to the pot. Add the sugar and spices and stir to combine over medium heat. The butter will need constant stirring at this point, or it will splash all over your stovetop.

Typically, I'm quite pleased with the consistency at this point, but if you find that it is too runny for your tastes, continue to cook, stirring all the while, until it reaches your desired thickness.

For a perfectly smooth butter, use an immersion blender to even out the texture just before canning.

Funnel the butter into clean, hot jars, leaving 1/2 inch headspace. Wipe the rims, apply the lids and rings, and process in a boiling water bath canner for 15 minutes.

When the time is up, remove the jars and set them on a folded kitchen towel to cool. When the jars have cooled enough that you can comfortably handle them, check the seals. Sealed jars can be stored at room temperature for up to a year. Any unsealed jars should be refrigerated and used promptly.