Place all ingredients except vanilla in pressure cooker insert pot. Stir together.
Seal the lid and close the pressure valve. Using the high pressure Manual button, set the time to 10 minutes if using canned pumpkin and 13 minutes if using fresh pumpkin. When the timer goes off, allow the pressure to release naturally for 15 minutes. Then press Cancel button. Place hot pad or dish towel over steam vent, and carefully open steam valve.
Stir to combine, and allow to cool slightly. Add vanilla. Use a hand blender, or transfer contents of pot to blender or food processor. Puree until completely smooth. Butter will thicken slightly as it cools.
Store in jars in fridge for 2-3 weeks.
Here's the Instant Pot I have and use for this recipe.