Peeled and cut the potatoes. Put in a large pot of lightly salted water and bring to boil. After 5 minutes add the sweet potato pieces and continue cooking until both are well cooked. Usually, that is another 15 minutes.
Pour the potatoes into a colander and let drain and evaporate. Put them back in the pot and puree them with the help of a potato masher. Add (optional) the salt and season to taste with pepper and nutmeg. Stamp again well and let cool to room temperature.
In the meantime, preheat the oven to 200 ° C / 390 ° F. Line a baking tray with parchment paper.
Put the mashed potatoes in a piping bag with a nozzle. Pipe the Duschess potatoes in rows on the baking paper. Keep approximately 2 cm distance between each turret.
Bake the Duchesse potatoes for 15-20 minutes in the preheated oven. When the outside begins to form a crust, they are ready. Eat them immediately after baking. No, not on your own 😉