Combine the milk, oil, salt and 1/2 cup water in a medium saucepan and bring to a boil while whisking.
Remove from the heat and pour over the tapioca flour in the mixing bowl.
Begin to mix, first starting on low, then gradually increasing the speed to high as the mixture begins to thicken and turn smooth.
(The mixture will look almost like glue.) While still beating, add the egg and beat until incorporated.
Then add the cheeses, a small handful at a time, beating, until incorporated. (The mixture will by sticky and slightly stiff.)