Trim the mugwort, wash thoroughly, and remove excess water.
In a bowl, mix oatmeal, cake flour, baking powder, and salt.
Cream the room temperature butter and sugar together.
Add the egg, mix well, then add the mugwort and dry ingredients and combine.
Take a portion of the dough, shape it into balls of appropriate size.
Place the dough on a baking sheet and bake in a preheated oven at 170°C for 15 minutes.