Preheat oven to 425°F and line a muffin tin with 12 liners. If using, prepare the cinnamon filling, set aside.
In a medium bowl, whisk together cassava, oat, and almond flours, collagen, coconut sugar, baking powder, salt + cinnamon.
In a small, separate bowl, melt the coconut oil and let cool for a few minutes. To the same bowl, add the maple syrup, greek yogurt, and vanilla. Whisk together. Add the eggs, gently combine.
Combine the liquid and dry ingredients until no flour remains (don’t over mix — banana chunks are fine!).
Place a small scoop of batter to each prepared muffin cup, filling about halfway. Add a layer of the cinnamon filling on top of each muffin. Place another small scoop of batter on top of each muffin. If you have filling left over, sprinkle on top of each muffin!
Bake for 5 minutes at 425°F (keep the door shut). After 5 min, bring the temp down to 375°F and bake for an additional 15 minutes. Every oven is different, take a peek at 12 min, use a toothpick to see if they are done. If not, go to 15 min.