How to Make It
Combine all ingredients except thyme leaves in inner pot of a 6-quart Instant Pot®. Close and lock the lid of the Instant Pot®. Turn the steam release handle to "Venting" position. Press [Slow Cook], and use [Adjust] to select "Less" mode. Press [-] or [+] to choose 6 hours cook time. When time is up, turn cooker off. Remove lid. Discard bay leaf.
Purée squash mixture with an immersion blender until smooth. Ladle soup into bowls. Garnish with thyme leaves, if desired.