Preheat the oven to 200°C.
In a bowl, combine cake flour, baking powder, sugar, and salt.
Add cold butter, cut it into small pieces, and mix into the flour.
Add milk and egg, then knead the dough together.
Roll out the dough to 2cm thickness and shape it into rounds.
Place the shaped dough on a parchment-lined baking tray.
Bake in the preheated oven at 180~200°C for 15~20 minutes.