In 6-quart or larger Instant Pot, turn on saute setting and add butter to inner pot. Add in diced onions and cook until soft, about 3-4 minutes. Add minced garlic and cook an additional minute, stirring constantly.
Add diced potatoes, cream of chicken soup, chicken broth, salt and pepper. Stir well. Place lid on Instant Pot and turn the vent to sealing. Set Instant Pot for High Pressure and set timer for 10 minutes.
When timer goes off, quick release the pressure. In small bowl, combine milk and flour to create a slurry. Once pressure is released, open the lid and stir in the slurry. Change cook mode to Saute and cook 4-5 minutes, until thickened. Stir in shredded cheese.
Serve with additional shredded cheese, bacon pieces, or green onion.