Turn your Instant Pot onto saute mode and add the olive oil.
When the oil is hot add the zucchini, garlic, sweet onion, kosher salt, and black pepper.
Saute for about 5 minutes or until the onion and squash soften.
Turn off the Instant Pot and pour in the vegetable stock.
Add the lid to the Instant Pot, turn the nozzle to the seal position, and set the pressure high for 10 minutes. Keep in mind it can take 10-15 minutes to reach pressure in the Instant Pot.
When the cooking time is complete allow the steam to naturally release for 5 minutes and then turn the nozzle to vent to manually release the rest of the pressure.
When the lid unlocks, remove the lid, turn off the Instant Pot, and use an immersion blender (or pour the hot vegetables and stock into a high-powered blender) and blend until the soup is smooth. If you use a blender add it back to the pot.
Stir in the heavy cream, taste, and season with additional kosher salt and black pepper if needed.
Serve with pumpkin seeds, a drizzle of sour cream or heavy cream, or garnish with minced cilantro.