In a large stainless steel saucepan, combine prunes, 1 cup (250 ml) of the water and lemon zest and juice. Bring to a boil over medium-high heat. Reduce heat, cover and boil gently, stirring occasionally, until prunes are soft, about 15 minutes.

Working in batches, transfer prune mixture to a food mill or a food processor fitted with a metal blade and purée just until a uniform texture is achieved. Do not liquefy. Measure 6 cups (1.5 L) of prune purée. Place 3 clean 250 ml mason jars on a rack in a boiling water canner.

Cover jars with water and heat to a simmer (180°F/82°C). Set screw bands aside. Keep jars hot until ready to use. Preheating Bernardin® lids is not advised. The sealing compound used for our home canning lids performs better at room temperature than it does pre-heated in simmering water (180°F).

Simply wash lids in hot, soapy water, dry, and set aside until needed. Preheating can lead to less vacuum being achieved during water bath canning, and to buckle failures during pressure canning.

In a clean large stainless steel saucepan, combine prune purée, remaining 1/4 cup of water, honey, cinnamon, cloves, allspice and nutmeg. Stir until sugar dissolves. If desired, add 1/2 tsp (2 ml) butter or vegetable oil to reduce foaming. Bring to a boil over medium-high heat.

Reduce heat, cover and boil gently, stirring frequently, for 1 minute, until mixture thickens and holds its shape on a spoon. (To test for doneness, spoon a small quantity of cooked mixture onto a chilled plate.

When liquid does not separate, crating a rim around the edge, and the mixture holds a buttery, spreadable shape, the butter is ready to lade into jars and process.) Quickly ladle hot butter into a hot jar to within 1/4 inch (0.5 cm) of top of jar (headspace).

Using nonmetallic utensil, remove air bubbles and adjust headspace, if required, by adding more fruit butter. Wipe jar rim removing any food residue. Centre sealing disc on clean jar rim. Screw band down until resistance is met, then increase to fingertip tight. Return filled jar to rack in canner.

Repeat for remaining fruit butter. When canner is filled, ensure that all jars are covered by at least one inch (2.5 cm) of water. Cover canner and bring water to full rolling boil before starting to count processing time.

At altitudes up to 1000 ft (305 m), process -boil filled jars - 10 minutes.* When processing time is complete, remove canner lid, wait 5 minutes, then remove jars without tilting and place them upright on a protected work surface. Cool upright, undisturbed 24 hours; DO NOT RETIGHTEN screw bands.

After cooling check jar seals. Sealed discs curve downward and do not move when pressed. Remove screw bands; wipe and dry bands and jars. Store screw bands separately or replace loosely on jars, as desired. Label and store jars in a cool, dark place.

For best quality, use home canned foods within one year.

Processing: At altitudes up to 1000 ft (305 m), process -boil filled jars - 10 minutes - 10 minutes.

Altitude-adjusted processing table: At altitudes up to 1000 ft (305 m), process -boil filled jars - 10 minutes