Slightly adapted from: The Homemade Flour Cookbook
Preheat the oven to 300 F. Lightly grease an 8 x 8 inch baking pan.
In a medium bowl, stir together the walnut meal, arrowroot, cane sugar, cocoa powder and salt. In a separate small bowl, whisk together the walnut oil, vanilla and egg. Pour the wet ingredients into the dry ingredients and stir to combine.
Spread the brownie batter into the prepared baking pan. Bake for 38-45 minutes, or until brownies are set in the middle and pulling away from the pan a bit. Let cool completely before slicing. Store in an airtight container for up to 3 days.