Turn Instant Pot to Saute mode and add butter, onions, and garlic.Saute until the onions are just starting to become translucent.Add 3 cups of the chicken broth and frozen broccoli and bring to a boil.Lock lid in place then hit manual and adjust the time to 5 minutes.Once the Instant Pot completes the 5-minute cycle, place a dish towel on the valve and do a quick release (QR).Remove lid once the pin drops and add the rest of the chicken broth, heavy whipping cream, cream cheese, and spices.