Preheat your oven to 350°F (175°C) to ensure even baking.
Grease your 9x9 inch baking pan with a little coconut oil to prevent sticking.
In a large mixing bowl, combine the melted coconut oil, coconut sugar, and the pinch of sea salt. Add in the ripe bananas and mash them well. Whisk in the eggs and pure vanilla extract until everything is well combined.
In a separate bowl, mix together the coconut flour, tapioca flour, almond flour, instant coffee granules (if using), baking powder, and ground cinnamon. Stir until all the dry ingredients are evenly distributed.
Gradually add the dry ingredients to the wet mixture, stirring gently until just combined. Be careful not to overmix, as this can affect the texture of your cake.
Gently fold in the chopped walnuts, ensuring they are evenly distributed throughout the batter.
Pour the batter into your prepared baking pan, spreading it out evenly.
Place the pan in the preheated oven and bake for 25-30 minutes, or until a toothpick inserted in the center comes out clean.
Once baked, remove the cake from the oven and let it cool in the pan for about 10 minutes. Then, transfer it to a wire rack to cool completely. Slice it up and enjoy your Paleo Banana Coffee Cake with your favorite beverage!