Preheat oven to 375°. Prepare a 9 x 9 baking pan with parchment or lightly oil with palm oil and dust with sorghum, shaking off the excess.
Make the topping first: combine cookie crumbs, cinnamon, brown sugar and oil until a paste is formed.
Mix together palm oil and sugar until light and fluffy. Add in agave (or honey) and applesauce and mix – it will look streaky. Mix in water and vanilla. Fold in dry ingredients (except baking soda) and mix until incorporated. Mix in apple cider vinegar. Once incorporated, mix in baking soda. Pour into prepared pan and spread batter so it is even. Drop dollops of topping on to batter, spreading it over the top. Place in oven and bake 20-24 minutes, or until cake is risen and firm to the touch.
While cake is baking, make icing by mixing sugar, water, and vanilla together. Add water to thin enough so that icing is stringy but not too wet.
Once cool, top with icing. Serve immediately or freeze in pieces and warm as needed.