Preheat oven to 325° F
Combine walnuts, coconut oil, and maple sugar in blender and pulse until crumbly. Set aside.
In same blender, combine beans, agave, honey, vanilla, oil, and eggs. Blend until smooth.
Add coconut flour, salt, baking soda, and baking powder and blend again.
Grease 9x13 inch pan with sunflower oil. Pour in cake mixture.
Distribute crumble topping evenly on top of batter and swirl gently through the batter with a fork.
Bake for 45 minutes or until toothpick inserted comes out clean.