01 - Set the Instant Pot to Sauté mode. Add olive oil and heat until shimmering. Add diced onion, sliced carrots, and sliced celery. Sauté for 3–4 minutes, stirring occasionally, until vegetables begin to soften and onion becomes translucent.
02 - Stir in minced garlic and cook for 1 minute until fragrant, being careful not to brown the garlic.
03 - Pour in vegetable broth, dried Italian herbs, salt, black pepper, and red pepper flakes if using. Stir thoroughly to combine, using a wooden spoon to scrape up any browned bits from the bottom of the pot.
04 - Add refrigerated cheese tortellini to the pot. Secure the lid and ensure the steam release valve is set to Sealing position. Cook on Manual or Pressure Cook mode for 2 minutes at high pressure.
05 - Perform a quick release by carefully turning the steam release valve to Venting position. Wait until the floating pin drops completely before opening the lid.
06 - Stir in heavy cream, chopped spinach, and grated Parmesan cheese until well combined. The spinach will begin to wilt immediately from the residual heat.
07 - Let the soup rest on Keep Warm mode for 2–3 minutes until spinach is completely wilted and soup reaches desired creamy consistency. Taste and adjust seasoning with additional salt and pepper if needed before serving hot.