Cream the butter with a hand-held mixer for a minute. Then add in both sugars and cream together for 2 minutes more.

Add in the vanilla and egg. Mix until everything is well blended.

In a separate bowl whisk together the oats, flour, baking powder, salt and cinnamon.

Add the dry mixture into the wet in stages while mixing until it's all added and combined.

Gradually fold in an optional add in, if using (Raisins are what's pictured).

Dough will be very thick and sticky. Cover and place in the fridge for at least 30 minutes.

Roll the chilled dough into small balls and set on prepared cookie sheets, about 2 inches apart.

Cook for 8-10 minutes. Cookies should only be very lightly browned around the edges and will still look very soft in the center. Let cool on baking sheet for 5 minutes, then transfer to a cooling rack to cool completely.