Get the sesame caramelized as follows: In a pot, add the water, the sugar and stir constantly until sugar melts. When boiled, add the sesame and keep stirring until the sesame roasted and caramelized. Then apply it on a flat surface covered with silpat or in a plastic tray and let it cool.
Break the chocolate into very small pieces (or grate it from the thick side of the grater) and put it in a bowl. Then add tahini.
In a pot, add the milk cream, boil it and pour it into the bowl with the chocolate and the tahini. Stir the mixture with a spatula until the chocolate melts and the tahini dissolves.
Pour the mixture into a shallow baking pan and let it cool- but not frozen.
By hand or spoon, take small quantities of the mixture and mold small balls.
Roll one by one the truffles in the caramelized sesame so as to be covered from all sides.
Put the truffles in the fridge in order to tighten.