(From The Foods & Wines of Spain, by Penelope Casas, Knopf, 1982)
Quince (membrillo) is a favorite in Spanish cuisine. Try this easy to make marmalade on bread, with a soft cheese on crackers, or on puffy pastry for Banda de Almendra.
2 quince (about 1-1/2 pounds) peeled, cored, and cut in 1/2-inch rings
10 tablespoons sugar
Place the quince in a saucepan with water to cover. Bring to a boil, then cover and simmer about 15 minutes, or until the quince are tender. Drain. Transfer to a food processor or blender and puree. Gradually beat in the sugar. Return the mixture to the saucepan and cook very slowly for 20 minutes, stirring frequently. Cool, then store, refrigerated.