Combine oatmeal, flour, and baking powder in a bowl.
Add butter and sugar and cream together.
Add the egg and mix well.
Add the oatmeal mixture and mix once more.
Shape the dough into bite-sized balls.
Place the cookie dough balls on an oven tray.
Bake in a 180°C oven for 12–15 minutes.
Cool on a wire rack.