In a large, heavy-bottomed pot, combine chopped pears and sugar. Cook over medium heat until the fruit can easily be smashed with the back of a wooden spoon. Use a potato masher or immersion blender to break the fruit down into a mostly-smooth sauce.

Add cinnamon and lemon juice and stir to combine. Continue to cook until the jam looks thick and passes the plate test.

Fill jars, wipe rims to remove any residual jam, apply lids (heat canning lids in a small pot over very low heat while you’re preparing the jam to ensure a good seal) and screw on the rims.

Process the filled jars in a boiling water canner for 10 minutes (start the timer when the pot has returned to a boil). When the time has elapsed, remove jars from pot and place the jars on a towel-lined countertop. Let them cool undisturbed for at least two hours. During this time, the lids should seal. Check to ensure the jars have sealed by pushing down on the center of the lid. If it feels solid and doesn’t move, it is sealed.