It's that time of year again - the hard squashes are in! I'll be stocking up this week, while they are on sale at the grocer, but on Nov 1 your can probably get 'Halloween Pumpkins" for free at pumpkin patches. Not the best tasting flesh, but great for seeds (especially the tiny ones).
I usually just keep them fresh, if you buy good quality ones they don't go bad quickly. But I have canned them if I have a bunch and several go bad at once.
Always can cubes - home canning puree doesn't work, you risk botulism. You do NOT want to risk that.
Clean 'em of strings and seeds, wash 'em, cut 'em into 1 inch cubes, remove rind. Boil for 2 minutes. Fill jars with the cubes and the water you boiled them in, leaving 1 inch at top of jar. Add tops/rings.
Pressure can at 10 pounds (15 if over 1000 feet) pints for 55 minutes, quarts for 90 minutes.