Add all of the ingredients to the bowl of the Instant Pot, just holding back about a third of the cheese. Mix thoroughly, and scrape down the sides so that everything is just submerged in the liquid. Sprinkle the remaining grated cheese on top.
Place the bowl into the Instant Pot, and close the lid. Make sure the valve is set to 'sealing'. Set the Instant Pot to 'pressure cook' - high pressure, normal mode. Set the Instant Pot to cook for 20 minutes (it will also take an additional 10 minutes or so to come to pressure), and leave it to cook.
When the Instant Pot has finished cooking, carefully perform a quick pressure release, and remove the lid. Serve warm.
Please make sure you read the manual of your Instant Pot before attempting to cook with it, and follow all safety recommendations.