Preheat oven to 350 degrees F. Line a baking sheet with parchment paper and set aside.
In a large bowl, combine the unsweetened applesauce, coconut oil, vanilla extract, and eggs. Add in the flour, oats, brown sugar, baking powder, baking soda, salt, and cinnamon, and stir until combined. Gently fold in the blackberries and walnuts.
Scoop ¼ cup of batter for each cookie onto the prepared baking sheet. Bake 18-20 minutes, or until browned around the edges. Cool on the pan for 5 minutes before transferring to a wire rack.
*To store, place in an airtight container and store in the refrigerator for up to one week.