Pre-heat the oven to 175°C.
Grease 2 baking sheets.
Cream the butter/margarine and sugar together with an electric whisk until pale.
Using a wooden spoon, mix in the sifted flour and cocoa until they form a paste.
Shape into small walnut sized balls (should make 15 - 20). I use a couple of teaspoons but you can just use your hands if you wish.
Roll the balls in the plate of oats to coat.
Place the balls on the baking sheets and press down with a fork on each one.
Decorate with a chocolate chip if wished.
Bake for 14 - 15 minutes in the centre of the oven.
Once ready remove from the oven and leave for a minute to cool. Then Transfer the cookies with a palette knife to a wire rack to cool.