Stew with cooking apples if you don't have many or stew on its own and use with meats instead of apple sauce.
or make confits by stewing the quince then passing through a fine sieve (a lot easier of broken up in a blender first but not mandatory). Add an equal weight of sugar and simmer stirring all the time until the mixture draws away from the side of the pan.
Pour onto a sheet of grease proof paper an place in airing cupboard for a day to set.

Slice, dust with icing sugar and store in an airtight container.