step 1 Heat the oven to 220C/200C fan/gas 7. Oil or butter a baking sheet and set aside. step 2 Heat the milk, butter and salt in a medium saucepan and bring to a boil. Remove from the heat and add the tapioca flour. Stir vigorously, then leave to cool a little. step 3 Pour the dough into a standing mix to beat the dough until its cool, or use a wooden spoon and beat by hand. Beat the eggs in one at a time, waiting until each is completely incorporated before adding the next. When the dough is glossy and mixed, add the parmesan. Beat again until mixed. step 4 Spoon the dough onto the baking sheet in 1 tbsp balls, 5cm apart. Bake for 30 mins until crisp and golden. Remove from the oven and eat while still warm.