Turn the Instant Pot to the saute setting and heat the oil for 1-2 minutes.
Add in the celery, carrots, and onions and cook for 5-7 minutes.
Add the garlic and cook for an additional minute.
Add the tortellini, broth, water, salt, and pepper.
Cover, set the valve to sealing and cook on manual high pressure for 4 minutes.
When the cooking time has finished, do a quick release of the pressure by switching the valve to the venting position.
Add the spinach and the cream and stir-- the spinach should wilt almost immediately.
Serve, garnished with grated parmesan cheese, if desired.
Store in an airtight container in the fridge for up to 4 days.