Turn on the Instant Pot and choose the Saute mode. Add the butter, onions, and garlic to the pot.
Cook the onions and garlic until the onions start to look a little see-through.
Now, it's time to add 3 cups of chicken broth and the frozen broccoli. Give it a good stir and wait for it to start boiling.
Lock the lid in place and press the Manual button. Adjust the time to 5 minutes.
When the 5 minutes are up, carefully put a dish towel on the valve and do a quick release. This means letting the steam escape quickly.
Once the pin drops down, it's safe to open the lid. Add the remaining chicken broth, heavy whipping cream, cream cheese, and spices.
Switch the Instant Pot back to Saute mode and wait for the soup to boil.
Now, it's time to add the cheese. Slowly pour it in while stirring the soup continuously.
Keep stirring until the cheese melts and the soup becomes smooth and creamy.
Once the cheese has fully melted, switch the Instant Pot to the Keep Warm setting.
Sprinkle the Xanthan Gum on top of the soup and stir it. This will help thicken the soup. Let it sit for about 5 minutes.