Hungarian Szilvásgombóc (Plum Dumplings)

Ingredients:

For the dough:

• 1 kg (2.2 lb) potatoes
• 250–300 g (2–2½ cups) all-purpose flour
• 1 egg
• 30 g (2 tbsp) butter
• Pinch of salt

For the filling:

• 12–15 ripe plums
• Sugar cubes (one per plum)
• Ground cinnamon (optional)

For the coating:

• 150 g (1½ cups) breadcrumbs
• 50 g (3½ tbsp) butter
• Powdered sugar for serving