Place your trivet or steamer basket into your Instant Pot. Add water and squash. Close lid and set valve to sealing.
To cook butternut squash halves, set your Instant Pot to manual mode, high pressure for 12 minutes.
Once the manual cooking program finishes, wait 5 minutes before you perform a quick release of the pressure. This adds up to about 25 minutes time spent in the Instant Pot as it can take up to 10 minutes for the pot to reach pressure.
Carefully remove your squash halves to a large mixing bowl, and remove the shell pieces carefully with either a spoon, paring knife, or by hand.
To cook peeled butternut squash 1″ cubes, set your Instant Pot to manual for 6 minutes, and perform a quick release. This is the cooking time I recommend you start with, and you can always adjust the cooking time to personal preference.