Combine oatmeal, flour, and baking powder in a bowl and mix.
Soften the butter at room temperature, then cream together with sugar.
Add the egg and mix well.
Add the oatmeal mixture and finish the dough.
Optionally add nuts or raisins to your liking.
Scoop the dough by spoonfuls and place them on a baking tray.
Bake in a preheated oven at 180°C for 12~15 minutes.