Boil the chicken breast for a long time, untilit becomes very very soft. Then separate the meat by hand into very small fibers (or you can use a blender). Wash 3-4 times, to remove any smells and juices from boiling. Drain well by squeezing it through a sieve.
In a bowl, mix the rice flour and potato flour. Heat the milk in a pan, and add the sugar and salt. Add some of the heated milk to the bowl with the flour, and mix until absorbed. Add the flour mixture to the pot with the rest of the milk and stir constantly until the cream starts to set.
Once the cream is starting to set, lower the heat. Take two generous spoonfuls of the cream and add it to the chicken. Mix, then add the chicken mixture in the pot with the cream. Stir constantly until the cream starts to set very very well.