For the Carinthian Kasnocken, mix all ingredients and knead into a smooth dough until firm and chewy. Cover with plastic wrap and let rest for about 30 minutes.
Roll out thinly on a lightly floured work surface, cut out circles about 6 to 7 cm in diameter and top with the herb filling.
For the herb filling, sauté onion and leek in a pan with butter, let cool and mix with remaining ingredients and season to taste.
Brush edges with beaten egg (dough will hold together better) and fold dough together. Press the edges well and crendln (Carinthian expression for the special folding of the edges) the edges of the dough with your thumb.
Place the filled dumplings in boiling salted water and cook for about 6 to 7 minutes.
Serve with melted butter and some brown pasta mint.