Wash the mugwort thoroughly and remove excess water.
Mix flour, sugar, and salt together in a bowl.
Add mugwort, milk, and egg, and mix well.
Pour the batter into a small oven-safe dish.
Mix butter, flour, and sugar to make a crumble, then spread it over the batter.
Bake at 180°C for 25 minutes.
Let the pudding cool and transfer it to a plate.