Add all ingredients to a food processor and process until mixture comes together into a sticky ball. Do not over-process as the walnuts will break down too much and make the mixture difficult to hold together.
Line an 8 x 8 inch baking dish with plastic wrap or parchment paper.
Spread mixture into pan ensuring top is flat.
Freeze for at least 1 hour.
Remove from freezer and pan and cut into 12 brownies.
Store in an airtight container in freezer.*
*these are best directly from the freezer and may get too soft if left out for too long. They still taste delicious though!