Step 1

Place pears and 1/2 cup water in a large saucepan over medium heat. Cook until softened, about 20 minutes. Transfer pears to a blender or food processor; puree until smooth but not liquefied.

Step 2

Return pear puree to the saucepan. Add agave nectar, lemon juice, orange zest, vanilla extract, cinnamon, nutmeg, cloves, and allspice. Reduce heat to medium-low. Simmer pear butter until thickened, stirring frequently, 70 to 90 minutes.

Step 3

Wash and rinse six 1/2-pint jars, lids and rings; let jars and rings dry on a rack. Immerse lids in a dish of boiling water.

Step 4

Fill a large canning pot with water. Bring to a boil; cover and keep simmering.

Step 5

Fill the dry jars to 1/2 inch from the top with hot pear butter using a ladle and canning funnel. Wipe rims clean. Pick up lids using tongs; cap jars and screw on the rings. Use canning tongs to completely immerse jars into the pot of boiling water. Cover pot; boil jars for 10 minutes.

Step 6

Remove jars with your tongs. Let cool, about 24 hours. Check seals to make sure lids have sucked down; listen for a popping sound. Label jars and store.