Add the butter to the Instant Pot. Turn to Saute. 

When the butter has melted, add the garlic, onion, carrot and celery. Cook, stirring for 5 minutes.

Add the broccoli and cook 3 more minutes. Pour in the broth, sea salt and mustard powder. Close and lock the lid. Turn to HIGH pressure and cook 1 minute. 

When the time is up, allow the pressure to naturally release. 

Open the lid, turn the Instant Pot to Saute and add the cream. Whisk in the shredded cheese a little at a time. 

Remove from heat and blend to a creamy consitency using an immersion blender or high powered blender.

Serve.