Add half of the coconut flakes to a large frying pan and toast over medium heat for about 5 minutes or until golden brown. Then add it back to the bowl with the remaining untoasted coconut and mix together. Set aside.
Add the mashed potatoes to a large mixing bowl. Gradually add the icing sugar, mixing with a wooden spoon after each addition. The mixture will become runny at first and then thicken up again as you continue to add the sugar. Keep mixing until you have a thick mixture that holds its shape.
Take a small handful of the mixture (about 30-35g) and roll it into a ball with your hands. Then place it on the lined baking tray and flatten it into a disk shape. Repeat with the remaining mixture. You should end up with around 18-22 macaroons.
Place the baking tray in the freezer for 45 minutes.
Melt the chocolate in the microwave in 30-second intervals.
Dip each chilled potato disk into the melted chocolate and then into the desiccated coconut. I recommend placing the disk on a fork, submerging it in the chocolate, and letting the excess drip off. Then, place it in the coconut bowl and sprinkle coconut over the top and sides to ensure it's entirely covered. Carefully push the macaroon off the fork and back onto the baking tray.
Once all the macaroons are coated in chocolate and coconut, return them to the freezer for 10 minutes to set the chocolate completely.
Store the macaroons in an airtight container in the refrigerator.