In a medium bowl, stir the cake mix, vanilla, cinnamon and egg. Then fold in the SweeTango apples to combine.
Pour 1 ½ cups of water into your Instant Pot. Put a trivet at the bottom of your pot.
Spray your oven safe bowl and dump the mixture into the dish. Cover that with foil, and make a sling out of foil to lower it on to your trivet inside the Instant Pot.
Put the lid on the Instant Pot, close steam valve, and set to manual, pressure, high, for 28 minutes. Do a natural release.
Take out, remove foil, and let stand for 10 minutes on a cooling rack.