Cut a circle around the stem of the pumpkin using a serrated knife. Discard the stem and use a spoon to scoop out the guts and seeds, just like you would do on a jack-o-lantern. Discard those as well.
Pour 1 1/2 cups of water into your Instant Pot. Place pumpkin with the opening facing up on a trivet and lower it into the pot. Place the cover on the pot and set timer to 15 minutes on high pressure (use the pressure cook setting). It will take the IP around 12 minutes to build up pressure before it begins cooking.
When the cook time is up, let the pressure release naturally for 5 minutes then do a quick release and allow the silver float valve to drop.
Poke a fork into the pumpkin to see if it is done cooking. The pumpkin should be fork tender. If it’s not, cook on high pressure for an additional 5 minutes.
When the pumpkin is done cooking, carefully pull the trivet out of the pot and place the pumpkin onto a cutting board. Cut it in half lengthwise and separate the flesh from the outer skin and place the flesh in a fine mesh strainer. Allow the moisture to drain for up to 1 hour.
Add sugar and spices and mix.
Pour strained pumpkin into a blender or food processor and puree until smooth. Pour into jars.