Turn on saute mode on the Instant Pot. When hot add olive oil to the pot, then add onion and Italian sausage. Cook and crumble the sausage until cooked through. Drain excess oil, if necessary.
Add garlic, salt, and pepper, and cook for 30 seconds until fragrant. Turn off saute mode.
Add water to the Instant Pot and whisk to remove browned bits from the bottom. Pour in the pumpkin and the uncooked pasta. Do not mix.
Lock the lid and set the vent to sealing. Press the pressure cook or manual button and set the cook time to 8 minutes. It will take about 5-8 minutes for the pressure to build.
When the cook time is up, do a quick release of the remaining pressure. Remove the lid.
Add the heavy cream and parmesan cheese to the pot. Stir the pasta and let rest for 5 minutes for the sauce to thicken. Garnish and serve.
Notes
Use fresh Parmesan cheese when possible. Do not use the pulverized stuff in the green can.
For a year-round pasta, you can use butternut squash instead of pumpkin, or just use pumpkin puree.