Turn pressure cooker to saute and let heat. Add in sausage and cook until browned and cooked through. Remove cooked breakfast sausage from the instant pot. Turn the Instant Pot OFF.
Add in 1.5 cups cold water to the Instant Pot and scrape up any browned bits on the bottom of the inner pot to prevent burn notice. Place the trivet inside the inner pot.
Whisk together eggs with milk and salt and pepper until well combined.
Lightly grease an oven-safe 7 by 3 inch baking dish. Cover the bottom of the pan with defrosted hash browns. Sprinkle sausage over hash browns. Pour eggs mixture over sausage and hash browns. Sprinkle with cheese and cover with foil.
Place casserole on a trivet in the pressure cooker. Cook on High Pressure for 20 minutes, using the manual button. Some people find 25 minutes is more to their liking.
Allow pressure to release manually for 5 to 10 minutes and then do a quick release and serve.
Be sure your hash browns are fully defrosted. If not, this casserole will take MUCH longer to cook.
If you use a super heavy duty foil to cover this casserole, you will want to increase cook time by 5 minutes.
If you happen to only have a 6-inch pan, increase cook time to 23 minutes on high pressure.
I have made this with tater tots in place of hash browns. I used one layer of FROZEN tater tots and then cooked for 25 minutes on high pressure.