Step 1Heat the oven to 375 degrees. Combine the water (or diluted wine), sugar, zest, cinnamon and spices in a saucepan and bring to a boil. Stir to dissolve the sugar, then simmer over low heat while you prepare the quince.
Step 2Peel the quince, cut them into wedges about three-fourths-inch wide at the center and remove the cores; you should have about 4 cups. Put them in a shallow dish, like a gratin dish. Pour two-thirds of the syrup over the fruit, including the spices. Bake, uncovered, for about 2 hours, turning the fruit every 30 minutes for the first 1½ hours and then more frequently during the last 30 minutes, as the syrup will be well-reduced by then. You want it to caramelize and thicken but not burn. When done, the quince should be nearly translucent and slightly rosy.
Step 3Remove from the oven and immediately add the dessert wine. At this point, you can serve either warm or at room temperature, or refrigerate, covered with the syrup.