Preheat the oven to 350ºF. Line a baking sheet with parchment paper and set aside.
Beat together the cashew butter, syrup, egg and vanilla. Once smooth, beat in the flour, baking soda and salt.
Fold in the blackberries.
Scoop the dough onto the baking sheet. Lightly flatten them with your hands.
Bake on the center rack for 10 - 11 minutes until the cookies are golden brown. Remove and allow to cool completely before digging in (this will make sure the cookies don't fall apart when you eat them)!
You want the nut butter to be fairly thin and creamy. If yours is on the thicker side, you might want to use 1 full cup of nut butter
Store these blackberry cookies in an airtight container at room temperature for about 3 days. They can also be refrigerated for up to a week.