Melt butter in a large skillet over medium heat. Add sugar, dates, walnuts, and beaten egg. Bring to a boil, stirring occasionally. Boil until dates have softened and melted into the mixture, 3 to 5 minutes. Remove from the heat and stir in rice cereal.

Place coconut in a shallow bowl.

Scoop rounded teaspoonfuls of dough and drop them into the coconut, rolling and pressing until coated.