Blanch the squash cubes 2 minutes in boiling water.
Pack into half-litre (US pint) jars or 1 litre (US quart) jars.
Leave 3 cm (1 inch) headspace.
Top up with clean boiling water (such as from a kettle, for instance), maintaining headspace.
Debubble, adjust headspace.
Wipe jar rims.
Put lids on.
Processing pressure: 10 lbs (69 kPa) weighted gauge, 11 lbs (76 kpa) dial gauge (adjust pressure for your altitude when over 300 metres / 1000 feet.)
Processing time: half-litre (US pint) jars for 55 minutes OR 1 litre (US quart) jars for 90 minutes.
Notes
Wash the squash before peeling, so that you aren't driving surface bacteria into the flesh as you peel.Don't blanch the squash for longer than 2 minutes, or it will break down a lot.Tip! If you are doing a lot, it can help to prep all the squash cubes the day before and store overnight refrigerated in large bags. The next day, bring out of the fridge about an hour before use to warm up, then proceed with the blanching of it.