Boil the unpeeled potatoes in salt water until they are soft.

Peel and dry in a 200 °F (100 °C) oven.

Press through a potato ricer and quickly knead with potato flour, egg yolks, semolina, butter, and a dash of salt.

Roll the potato dough out to about 4mm thick on a floured work surface.

Cut out circles with a 3in (8 cm) round, scalloped cookie cutter.

Mix the plum jam with cinnamon and rum and place in the middle of each circle (preferably with a piping bag).

Brush the edges with a beaten egg, close the dough, and press the edges together with your thumb and forefinger.

Boil salt water and place the pockets in the water for about 5 minutes.

For the crumbs, heat butter and brown the crumbs.

Remove the pastry pockets from the water, let drip, and roll in the crumbs.