Place potato chunks in the Instant Pot (or any electric pressure cooker), add the kosher salt and the water. Process on manual for 8 minutes (or high/15 psi on other pressure cookers)
Release pressure and drain potatoes well.
Using a hand masher, lightly mash the potatoes. Add just enough of the warm milk so the potatoes are creamy but not soupy. You may not use the entire amount, or you may need more warm milk, depending on how creamy you like them.
Add the butter, toasted onions, garlic and parsley. Stir to combine.
Add salt and pepper to taste.
If you cannot find toasted instant onions, then 2 tbs of minced caramelized onions can be substituted. In a pinch, you can use finely chopped green onion or regular dehydrated minced onion.