Preheat your oven to 400 degrees. Lightly grease a 24-well mini-muffin pan with cooking spray or oil.
In a blender, combine the flour, milk, vegetable oil, egg, and salt. Process until smooth, scraping down the sides as needed, about a minute or so. Add the cheese and pulse once or twice more, until just combined.
Divide the batter evenly into the greased mini-muffin pan. Bake for 15-20 minutes, or until puffed and golden. Baking for less time will give stretchier, chewier rolls, and more will give a crispier exterior. Serve warm. Leftovers can be frozen and reheated at 400 for 5 minutes.
Using a blender helps fully emulsify and aerate the batter, especially as the tapioca flour has a cornstarch-y consistency that can be difficult to mix by hand. That said, you should be able to use a food processor, stand mixer, or electric beater to achieve the same effect.
In terms of variations, other cheeses–cheddar, or Monterey Jack, for example–or different types of milk will work, and replacing a few tablespoons of the milk with sweetened condensed milk nicely complements the tapioca flour’s natural sweetness. However, do keep the amount of egg and oil the same, as that can affect how well the puffs rise and hold their shape, interestingly.