Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

In a medium bowl, mix together the rolled oats, flour, baking soda, salt, and ground cinnamon.

In a large bowl, whisk together the melted coconut oil, brown sugar, and granulated sugar until smooth. Add the egg and vanilla extract, mixing until fully incorporated.

Gradually add the dry mixture to the wet mixture. Stir until just combined; don't overmix. Gently fold in the cranberries and walnuts.

Using a tablespoon or cookie scoop, drop spoonfuls of dough onto the prepared baking sheet, leaving space between each cookie as they will spread slightly.

Place in the oven and bake for about 12-15 minutes, or until the edges are golden brown.

Remove from the oven and let the cookies cool on the baking sheet for about 5 minutes before transferring them to a cooling rack.