Preheat your oven to 375°F (190°C). Line a baking sheet with parchment paper.

In a medium saucepan, combine the milk, oil, and salt. Place over medium heat and bring to a boil, stirring occasionally.

Once it boils, remove the saucepan from the heat and slowly add the tapioca flour, stirring constantly until smooth. The mixture will be sticky.

Transfer the dough to a mixing bowl. Let it cool slightly, then beat in the eggs one at a time until fully incorporated.

Stir in the parmesan and mozzarella cheese (if using) until well combined.

Using your hands, scoop out tablespoon-sized portions of the dough and roll them into balls. Place each ball onto the prepared baking sheet, leaving space between each roll.

Bake in the preheated oven for 20-25 minutes, or until the rolls are lightly golden and puffed.