Boil the potatoes in salted water until they soften. Meanwhile, preheat the oven to 200˚C (fan-forced).
Mash the potatoes and mix in all the remaining ingredients, except for the garnish ingredients.
Transfer the mashed potato mixture into a piping bag, then pipe it onto a baking tray. Brush the piped potato mix with butter.
Bake for 15-30 minutes, or until the potato turns golden. Garnish and serve.