Preheat oven to 350 F.
For the sauce-melt butter over a medium heat in a saucepan. Add sugar and maple syrup. Stir for 3 minutes or until bubbling but do not burn.
Pour the sauce into an 8-inch cake pan and coat the base well. Arrange
bananas in staggered overlapping rows, covering bottom of pan evenly.
In a large bowl, cream 8 tablespoons of butter, sugar and lemon zest. Add eggs, one at a time, beating until combined after each. Mix in the
mashed banana until combined.
In a medium bowl, whisk together the cake flour, baking powder, salt, and cinnamon.
Add flour mixture to butter mixture in three batches, alternating with the milk and starting and ending with the flour.
Sprinkle shredded coconut over the bananas in cake pan. Pour batter into cake pan, and spread evenly over coconut and bananas.
Bake until a toothpick inserted in center of cake comes out clean, about 50 minutes (my oven was about 40 minutes). Invert cake carefully onto serving plate.