Preheat the oven to 180°C (356°F) and grease a bread pan. Line it with baking paper, leaving the ends uncovered.
In a medium bowl, combine almond flour, tapioca flour, salt, chemical yeast, and cinnamon. Use a fork to mix well.
In a larger bowl, mix together monk fruit sugar and softened coconut oil until creamy using a wire whisk.
Add the eggs to the coconut oil mixture and continue whisking until homogeneous and shiny.
Gently fold in the mashed bananas.
Gradually add the dry ingredients from the medium bowl to the wet mixture. Mix until just incorporated.
If using walnuts, fold them into the batter.
Pour the batter into the prepared bread pan.
Optionally, place a halved banana on top of the batter.
Bake in the preheated oven for 40 to 50 minutes, or until the surface is well-browned and a toothpick inserted into the center comes out clean.
Allow the banana bread to cool in the pan for about 15 minutes, then transfer it to a rack to cool completely.