Unsweetened Pear Sauce

Ingredients
Pears (~4 lbs per quart of pear sauce)
Cinnamon (optional!)

Directions 
1. Pick sweet pears to cut down on the added sugar. Some of the common sweet varieties are Bartlett, Bosc, D'Anjou and Asian pears.
2. Wash the pears in plain cold water and remove any stickers or labels on them. If not using a sieve, peel the pairs using a vegetable peeler or a paring knife, and remove the stems.
3. Chop the pears. A pear corer/segmenter will work faster than by hand. Remove any mushy or dark areas.  If not using a sieve, also remove any seeds and hard parts (usually the part around the seeds).
4. Put about 1 inch of water (or pear juice) on the bottom of a huge, thick-bottomed pot, and add the pears. Turn heat on high, with the lid on, until the pot starts to boil. Then turn heat to medium high until the pears are soft through and through.
5. Sieve the cooked pears if the skin, seeds, hard parts, and stems were not removed.
6. Put the pearsauce into a large pot and add cinnamon to taste.  Keep the pears hot until added until the canning process.
7.  Fill canning jars to within ¼-inch of the top, wipe any spilled pear sauce of the top, seat the lid and gently tighten the ring around them. Put them in the canner and keep them covered with at least 1 inch of water. Get the canner back to a full boil and begin timing. If you are at sea level (up to 1,000 ft) boil pint jars for 15 minutes and quart jars for 20 min. If you are at an altitude of 1,000 feet or more, see the chart below . Recommended process time for pears auce in a boiling-water canner. Process Time at Altitudes of Quart Size 0 - 1,000 ft 1,001 - 3,000 ft 3,001 - 6,000 ft Above 6,000 ft Pints 15 min 20 20 25 Quarts 20 25 30 35
8.  Lift the jars out of the water and let them cool without touching or bumping them in a draft-free place (usually takes overnight).  Loosen the canning rings to prevent rusting due to trapped moisture.  Once the jars are cool, you can check that they are sealed verifying that the lid has been sucked down. Just press in the center, gently, with your finger. If it pops up and down (often making a popping sound), it is not sealed. If you put the jar in the refrigerator right away, you can still use it. Some people replace the lid and reprocess the jar, then that's a bit iffy. If you heat the contents back up, re-jar them (with a new lid) and the full time in the canner, it's usually ok.

NOTES
Recipe from here.