Preheat the oven to 170°C (338°F).
Sift the mugwort powder, flour, baking powder, and salt together.
In a bowl, whisk together the eggs and sugar.
Add the sifted dry ingredients to the egg mixture and mix with a spatula.
Add the nuts and chestnuts and finish the dough.
Shape the dough into a long log on a baking tray.
Bake the dough in the oven at 170°C (338°F) for 20-25 minutes for the first bake.
Let it cool, then slice into 1 cm thick pieces.
Place the slices back on the tray and bake again at 150°C (302°F) for another 10-15 minutes.