Place a trivet in the inner pot of your Instant Pot. Add 1 ½ cups of water.
Place the frozen ham on a large sheet of heavy duty aluminum foil. Fold up the sides of the foil, forming it around the ham. Drizzle with melted butter, then sprinkle with brown sugar, pressing it against the ham to help it stick. Set the foil-wrapped ham on the trivet.
Secure and seal the lid, then cook on Manual High Pressure for 35 minutes, allowing a full Natural Release.*
Allow the ham to rest for 10 minutes before serving.
Notes
* if the ham isn't 145 degrees once cooking is done, place back in the Instant Pot and cook for another 5 minutes.
This nutrition information is based on the exact products I used in this recipe. Brands and sizes of products could alter exact nutrition and should always be calculated independently.