Cook the hashbrowns in your instant pot with plenty of oil, also cook the diced onion. While cooking sprinkle with kosher salt to taste. Set aside (leave in Instant Pot liner with a lid on it).
Cook off your sausage patties to brown them to your preference. I used my cast iron griddle on my stove top to brown them nicely. Blot the oil and cut up into bite sized pieces.
Top the hashbrowns in your Instant Pot liner with the sausage pieces.
Sprinkle shredded cheese on the sausage pieces.
In a medium bowl, beat the eggs together with the milk, then pour right over the top of the potatoes and sausage layers.
Season with red pepper flakes, garlic powder, mushroom powder. No need to mix in.
Sprinkle the Parmesan on top.
Place the lid on the Instant Pot to lock. Close the valve (seal). Program slow cook for 4 hours on high, check if longer cooking is needed*
Open the pot and serve - add any additional salt/pepper to taste.
*Note: originally attempted this as a pressure cook without spring form pan/water bath but not enough liquid (and potentially the hash browns on the bottom) meant it could not get to pressure without the dreaded burn notice. Pivoted to slow cook on high checking hourly for done-ness since it was partially cooked from trying to pressurize.
