Melt butter in a frying pan over medium heat; add sugar and stir until well blended. Stir in rum; bring to a boil and simmer for 3-5 minutes.

Add chestnuts and stir until coated with the caramel mixture.

Line a cookie sheet with parchment paper; place individual chestnuts on paper and cool for about 1 hour, until coating has hardened. Serve as a delicious holiday snack, or a unique addition to your favourite salad.