Optional step: set the rolled oats in a large frying pan and cook while stirring until fragrant, about 3-5 minutes.
In a large bowl, melt the butter. Add the sugars, vanilla, cinnamon and salt and whisk until thick. Add the egg and whisk vigorously, for about 2 minutes until shiny.
Stir in the oat flour and baking soda then add the rolled oats and dried cranberries.
Cover the bowl to seal and leave at room temperature for about 20-30 minutes (this helps the flour hydrate).
Transfer the bowl to the fridge for an overnight chill (or at least 4 hours).
The next morning, preheat the oven to 350 F and line two greased cookie sheets with parchment paper.
Scoop the cookie dough onto the prepared pan, about 1.5-2 tablespoons of dough per cookie. If you like, you can roll the cookies in some additional rolled oats.
Bake for about 10-12 minutes, until slightly golden on the edges. If the cookies are a bit funky shaped and you’d like to round them: while they are still hot, place a bowl that’s slightly larger than the cookie over the cookie and move it around in circles (see the video for guidance).
Store cookies in an airtight container.