In a medium size pan, boil the potatoes for 15 minutes.
Strain the potatoes and add them to a bowl. Mash the potatoes until smooth. Then cover, and set aside in the fridge to cool.
Once the potatoes have chilled, add the flour and knead until a dough has formed. The dough shouldn't stick to your hands, so keep adding flour until it doesn't.
Meanwhile, add the cinnamon and sugar to a bowl and combine.
De-stone the plums by cutting around the whole plum leaving about 2cm uncut. Gently open the plum without pulling the two halves apart completely, and remove the stone (see video on Instagram).
Tear off a bit of the dough and flatten it out into a circular wrapper (around 3-4 inches in diameter) with your fingers and thumbs. Place the de-stoned plum into the centre of the wrapper with ½ teaspoon of cinnamon sugar (into the centre of the plum where the stone would have been). Then wrap the dough up around the plum and seal. Repeat until the plums and dough are used up.
Place the dumplings into a pan of boiling water and cook for 6 minutes.
Meanwhile, pour the breadcrumbs and butter into a frying pan and fry for 3 minutes so the butter is well incorporated into the breadcrumbs
Remove and coat in breadcrumbs.
Option to dust in icing sugar!