In a saucepan over low heat, melt the chocolate chips and butter, stirring constantly until smooth.
Remove from heat and allow to cool for 8–10 minutes so the marshmallows don't melt.
Gently fold in mini marshmallows and nuts (if using) until well coated.
Lay out two long sheets of parchment or wax paper and sprinkle coconut in two rows.
Divide the mixture into two logs and place over the coconut. Shape into logs and roll to coat evenly.
Wrap tightly and refrigerate for 2+ hours or until firm.
Slice into ½-inch thick pieces and serve cold.