I rinse the seeds thoroughly in water, then dry them in a food dryer (coat the screens with cooking spray so they don't stick). They keep well in an airtight jar or ziploc in the freezer. Then, I usually toast them in a little oil before serving.

I meant saving them to plant next year? :)

The technique for saving the seeds is not that difficult. Allow at least one squash to ripen on the vine, cure it for about a month after picking (which will improve seed vigor & storage life), then remove the seeds. Clean them as thoroughly as possible, then dry them until the seeds snap easily when bent. Keep them in an airtight container in your fridge for the best storage life.

But the real issue may be whether the seeds are worth the trouble. I am assuming that the squash was not a hybrid - if it were, the seed would not breed true next year, and should not be saved. The main problem with saving squash seed is cross-pollination.

Bees love squash blossoms, and will travel great distances for them. Spaghetti squash will cross with zucchini & most summer squash, acorn squash, most pumpkins, and small ornamental gourds - plants very commonly grown by gardeners. If you are in an urban area, or near other gardens (within 1/4 mile, and possibly more) the chances of crossing are very high.

If you wish to save seed, you would need to blossom bag & hand pollinate, to eliminate the possibility of crossing. There are several good threads on GW about this technique. If you are certain that there are no other gardens within the distance mentioned above, this may not be necessary - but I still recommend it, because bees sometimes travel over a mile for squash blossoms, and safe is better than sorry. There are several "weird squash" threads here that show the possible outcome, and Cucurbita pepo (which includes spaghetti squash) is the worst offender.

While hand-pollination can be time consuming, you may only need to do it every 5 years or so, if the seeds are stored properly.

hand pollenating is super easy. read up on it.

I had a female squash blossom and NO MALES. the squash was full of seeds. Guess What. IT must have been crossed with a male somewhere far away.

If you want to save seeds you must hand pollenate. nothing could be easier once you get the hang of it.