Preheat oven to 350F and spray an 8 or 10" cast iron skillet with non stick cooking spray. I used coconut oil spray.
Toss the blackberries with 2 tablespoons of sweetener and place them in the skillet.
In a large bowl beat all wet ingredients: flax egg or egg replacer, butter, vanilla, and the 2 remaining tablespoons of sweetener.
Add in he almond and coconut flour and mix well until all is well combined and dough is formed.
Spread the dough evenly on top of the blackberries, pressing it down either with your spatula or your hands. Option to sprinkle the top with a bit more sweetener.
Place into the oven and bake for 20-25 minutes or until edges are golden and blackberries are bubbling. If you want to bake it more and it's darkening too fast, place foil on top of it and let it cook for the extra time so it won't burn.
Remove from oven and let settle for 5 minutes before serving. Top with coco whip, maple drizzle, some dairy free ice cream and you're good to go - Enjoy!