Clean the sweet potatoes under cold water with a soft bristled brush. Dry well with a paper towel. Then poke them all over with a fork.
Mix together the salt, cinnamon, and nutmeg in a small bowl. Separate the seasonings in half, and mix half of them in another small bowl with the brown sugar.
Rub olive oil all over the outsides of the prepared sweet potatoes. Use the other half of the seasonings to rub all over the outsides of the now oiled potatoes.
Air fry the sweet potatoes at 385 degrees Fahrenheit for 40 to 50 minutes, or until you can stick a fork into them and they feel tender.
Cut the sweet potatoes open down the middle, but not all the way through. Scrape out the sweet potato in the middle, and mash it in a bowl. Or use a fork to mix it all up inside each of the sweet potatoes. (Depending how soft and mashy you want the insides)
Sprinkle the brown sugar mixture evenly over the tops of each of the sweet potatoes.
Top each sweet potato with tiny pats of butter.
Return them to the air fryer and cook for another 2 minutes.
Sprinkle the marshmallows over the top of each of the sweet potatoes, and air fry for another 2 minutes, or until the marshmallows are lightly toasted.
Remove from the air fyer and top each with chopped pecans, and a drizzle of maple syrup.