Wash the potatoes and then use a cheese grater to shred them. Rinse the shredded potatoes and then let soak in a large bowl of water for one hour to remove some of the excess starch. Drain the water and squeeze you as much water as you can from the potatoes.
Add the butter to the Instant Pot® bowl and press the ‘saute’ button. Let the butter melt and then add the chopped onion. Saute for 5 minutes, stirring occasionally. Add the garlic and saute for another 2 minutes.
Turn off the Instant pot and add all of the remaining ingredients except for the sour cream and cheese. Stir well to combine.
Place the lid on the Instant Pot® and set the steamer valve to ‘seal’. Press the ‘manual’ button and set the cooking time to 2 minutes. Let the pressure naturally release (meaning wait another 10 minutes or so until you can open the lid of the pot).
Open the Instant Pot® and stir in the cheese and sour cream.
Transfer the potatoes to a casserole dish and sprinkle with the toasted bread crumbs. Serve while hot!