Preheat oven to 190 C.

Cream butter and sugars together until light and fluffy.

Add the eggs and vanilla and beat well.

Stir in the finely ground porridge oats, flour, baking soda, baking powder and salt.

Fold in the coarsely chopped chocolate.

Pinch off pieces of dough the size of a small walnut. Roll into balls and place on a baking tray 2 inches apart.

Bake for 10-12 minutes, until light golden. Leave to cool on the baking tray for a few minutes before transferring to a wire rack to cool completely.