Rinse apples, pat dry, and using a pairing knife make a round incision into the top of the stem going down and around in a circle into the core (but not coring all the way through, you want the bottom in tact so filling doesn't drain out).
Scoop middle of apple and seeds out so there is room for oat/sugar filling.
In a bowl mix oats, apple pie seasoning and brown sugar. Pour melted butter into this mixture and stir.
Fill inside of cored apples with about 2 tbsp of oat mixture until it is all gone.
Pour water into your pressure cooker and place a trivet into the bottom of the pot. Arrange the stuffed apples into your pot so they fit snugly next to one another.
Close your pressure cooker lid and steam valve and set to pressure cook high for 5 minutes. Do a quick release when done.
Carefully use tongs to remove each apple and on to a plate. Can put another pat of butter and more cinnamon on top, or a swirl of whipped cream or ice cream on top. Cut and enjoy.