I wonder if there is a halachic problem with having a fondue (cheese of chocolate) on yom tov? There are possibilities to either use a plata or a small burner with an open flame that of course won’t be extinguished. The fondue usually is prepared in advance, i.e. comes cooked on to the burner.
It is permitted to cook and warm up food on Yom Tov so therefore it does’t seem a problem to place the fondue on the burner. Enjoy!