On the Instant Pot, press on SAUTE - normal and heat the olive oil.
Saute the onion until it's soft and translucent, then add the garlic and cook for a minute or until it's fragrant.
Switch off the SAUTE setting. Add the cauliflower florets, vegetable stock, ground nutmeg, and season with salt and pepper.
Secure the lid and set the vent to SEALING. Select the PRESSURE COOK/MANUAL setting and set the cooking time for 7 minutes at high pressure. The Instant Pot will take around 5 minutes to come to pressure and start cooking. When the cooking program ends, leave it for a couple of minutes then quickly release the steam.
Carefully remove the lid, and with an immersion blender, blend the soup until smooth.
Stir in the heavy cream, and cheddar, and keep stirring until the cheese has completely melted. Adjust seasonings to your preference, serve warm.
Store the soup in the fridge for up to 3 days in an airtight container without the toppings.
Freeze in an airtight container for up to 3 months, reheat in the microwave or over the stovetop.
The cream and the cheddar are optional, but add a lot of flavor and creaminess. If you want to make this soup vegan, then skip these 2 ingredients and it will still taste delicious.