"Wacky Cake" that's gluten, egg and dairy free

So here is my tweak on the Wacky Cake I mentioned in March. It's gluten, egg and dairy free. And I think it's delicious.

1 1/2 cups buckwheat flour (this is not a grain but actually a seed)
1 cup coconut flour
1/2 cup oat fibre
1 1/2 cups xylitol
10 "donks" THM pure Stevia
2 tsp baking soda
2 tsp baking powder
1 tsp xantham gum
1 tsp salt
6 Tbs cocoa powder
1 cup apple-sauce (I just blend apples till they are liquid - no added sugar)
2 Tbs apple cider vinegar
2 1/2 cups cold water

Mix the dry ingredients together. Add the wet ingredients and mix well.
Pour into a lined tin. I use a bit oven tray - 25cm x 35cm.
Top with chopped up dark, sugar free, dairy free chocolate.
Bake at 180 C for around 20 minutes.