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.
Notes
Here's where to buy Otto's cassava flour. They provide the best price and free shipping.
Here is a great source for sustainable collagen and gelatin. Use code BEAUTIFUL10 for 10% off your entire order.