Add cut sweet potatoes and 1 cup water into the Instant Pot.
Make sure that the release valve is in the "Sealing" position. Place the lid on, turn and lock.
Press the "Manual" button on the Instant Pot on high pressure, and then set the timer to 10 minutes.
When the potatoes finish, quickly release the pressure and drain the water.
Place the potatoes back in the instant pot then mix together the sweet potatoes, sugar, eggs, salt, butter, milk and vanilla.
Mix until smooth.
Transfer to a 8x8 baking dish, 7" cake barrel air fryer accessory, or five 8oz ramekins.
In a small bowl mix together the brown sugar and flour. Cut in the softened butter to make a fine crumble. Pour on top of the sweet potatoes in an even layer and lightly press down.
Place in the air fryer and cook for 6 minutes at 320°F/160°C or until mixture is cooked through. add the marshmallows and chopped pecans to the top, press down lightly, and cook for an additional 3-4 minutes.