Preheat oven to 180°C and line a baking tray with parchment paper.
Mix the tapioca flour and salt together in a large bowl, create a well in the centre and set aside.
In a saucepan combine the milk and oil and slowly bring to a boil. Pour the hot liquid into the tapioca flour and mix well. Add the egg and stir again, the mixture should look similar to a thick Choux pastry. Stir through both the cheeses until incorporated and a slightly tacky dough forms.
Take a tablespoon of the mixture and roll into balls and place on the lined tray.
Bake in the oven for 20 - 25 minutes, until puffed up, lightly golden and oozy in the middle.
Eat warm so the cheese is melted and gooey. You also can reheat them before serving.
