1small bananamashed, or ¼ cup blueberries for lower carb version
Preheat oven to 350° F, and lightly grease a 9 inch cake pan.
Place 2 tbsp coconut oil into cake pan, and put pan into preheating oven for a couple minutes to melt oil. Once melted, make sure oil is evenly distributed all over the bottom of the pan.
Sprinkle 2 tbsp coconut sugar or xylitol all over the melted oil.
Sprinkle 1 tsp cinnamon on top of sweetener layer.
Layer banana slices or blueberries on top of butter- sweetener layer. Add optional walnut pieces to fruit layer. Set aside.
In a large mixing bowl combine all the top cake layer ingredients except for the coconut flour. Mix thoroughly, then add the coconut flour and mix well, scraping sides of bowl, and braking up any coconut flour clumps.
Spoon cake batter on top of fruit layer in pan. Spread cake batter evenly across entire pan.
Bake for 25 minutes or until top of cake is browned and center is set.
Remove from oven and let cool completely.
Use a butter knife between cake and edge of pan and slide around to loosen cake from pan. Turn cake pan upside down onto a large plate or serving platter. Cake should fall onto plate, but if not, then use a turning spatula to lift gently under cake a little, and then turn upside down onto plate.