Place the trivet in the liners of your instant pot. Pour in the water and place the squash on the trivet. Close the lid and set your IP to Sealing. Select Manual, high pressure, for 25 minutes. When the cook time has completed, Natural Release for a few minutes and then Quick Release the remaining pressure (if water spurts out when Quick Releasing, Natural Release for a few more minutes).
When the pressure has been released, remove the Instant Pot lid. Let the squash cool for a few minutes until you can handle it. Cut the squash in half (it will cut like butter). Scrape out the inner seeds. Then break up the strands with a squash. The squash skin will peel off easily so no “spaghetti” is wasted.
Serve with your favorite sauce or even as is with a little salt and pepper. Store in the refrigerator in an airtight container for up to 5 days.
My squash was 3 pounds, if yours is larger or smaller you will want to adjust your cook time slightly.