Quince paste (called Membrillo in Spain)

This recipe uses the large tree fruits, not the small ornamental quinces, which are not nearly so tasty.  Windfalls are good for this, just cut away the bruised parts.
quinces, washed, peeled, cored, chopped. Keep the peel and cores.
vanilla pod, split
sugar, equal to the amount of cooked quinces.
Place the quinces in a large pan. Add enough water to cover. Add the vanilla pod, put the peel and cores in a sheet of muslin tied with string and put this in the pan and boil.  (The peel and cores contain pectin, helping the jelly to set).  Place a lid on the pan and boil for 30-40 minutes, until the quinces are very soft.
Remove the vanilla pod and bag and discard. Drain the liquid from the quinces and weigh them. Note the weight – this is the weight of sugar needed.
Blend the quinces.  Some people like the paste very smooth, others prefer it to have more texture.
Return to the pan and add the sugar.  Heat gently, stirring constantly, until the sugar dissolves.
Simmer over a low heat, stirring occasionally, for 1-1½ hours, or until the quince paste has thickened and has become a deep orange colour.
Preheat the oven to 50C/120F.
Pour the cooked paste out onto a greased and lined baking tray and smooth the paste out evenly to about a half inch thickness.
Place into the oven for one hour to speed up the setting process.
Remove from the oven and slice into portions.  Put the slices into sealed containers and refrigerate.
They will keep for a long time if they are not allowed to dry out. Expect the slices to deepen in colour as they age.
Serve with cheese; the Spanish like to have it with Manchego. It can also be used as a breakfast spread on bread or toast.