Preheat the oven to 180°C (356°F).
Combine cake flour, green tea powder, baking powder, sugar, and salt in a bowl.
Add cold butter and cut into small pieces, then mix into the dough.
Add milk and egg, and gently combine to form the dough.
Roll the dough out to a thickness of 2cm and cut into triangles.
Line a baking pan with parchment paper and place the scones on it.
Bake in the oven at 180°C for 20 minutes.