Grease a 9"x9" (or 8"x8") casserole dish. Preheat oven to 350℉.
Combine dry ingredients in a large bowl: cassava flour, coconut sugar, tiger nut flour, collagen, coconut flour, gelatin, baking soda and sea salt.
In a medium sized bowl whisk together the wet ingredients, (excluding the blueberries): coconut milk, avocado oil, water, lemon juice, and lemon oil.
Pour the wet ingredients and the blueberries into the dry ingredients, folding together thoroughly without over-mixing. (I like to use an electric hand held mixer on Low speed. The batter will be thick and sticky.)
Scrape batter into prepared dish, spreading it and evening it out. Bake in preheated oven about 35 minutes, until golden brown around the edges and golden brown on top.
