To make the bottom layer, place the walnuts, dates, and 1/8 teaspoon sea salt in a food processor and pulse to break the ingredients down, till they're crumbled. Run the motor and process till the mixture is ground up and sticking together when you squeeze a little in your hand.

Press the bottom layer into a small casserole or baking pan that has been lightly greased with olive or coconut oil (I used 11" by 7.5"). Set aside while you make the top layer, or chill overnight.

To make the top layer, blend the cashews, blackberries, oil, remaining 1/8 teaspoon sea salt, and syrup in a high speed blender or food processor till they're as smooth as possible. Pour the top layer over the bottom layer in the pan. Use a spatula or inverted knife to smooth the top layer over very evenly.

Transfer the dish to your fridge and chill for at least three hours. Cut into bar shapes and serve.

Yields 15-20 bars, depending on how big you'd like them.