Grind the oats in a blender until they become powdery.
Mix matcha powder, flour, baking powder, and salt in a bowl.
Cut cold butter into small pieces and mix by hand until crumbly.
Add sugar and mix, then gently knead in the milk and egg.
Fold in the chocolate chips.
Flatten the dough and cut into your desired shapes.
Bake in a preheated oven at 180°C for 20 minutes.