Preheat oven to 180oC/350oF. Line oven trays with baking paper.
Beat butter, sugar and syrup in a small bowl with an electric mixer until smooth. Beat in eggs, one at a time. Stir in sifted flour and baking powder, then add the coconut and oats.
Roll rounded teaspoons of mixture into balls. Place about 5cm apart on trays. Flatten with a fork and bake for 12 minutes. Cool on trays.
Soften ice-cream slightly by removing from freezer at room temperature for 10 minutes. Top half of the cookies with ice-cream and gently sandwich with remaining cookies. Freeze until ready to eat.