Preheat oven to 400 degrees. Spray a mini (or about 7 wells of a regular-size) muffin tin with non-stick spray or rub with butter.
Place egg, milk, oil, tapioca flour, and salt in blender and blend until smooth. Add cheeses and pulse just a couple times.
Immediately pour batter into muffin tin. Fill each well about ¾ full. If desired, sprinkle a bit of parmesan cheese on top.
Bake for 15-20 minutes until puffed and golden. Remove from oven and cool for a few minutes before removing rolls from pan. Serve warm.
