Preheat the oven to 350 degrees. Line a 9x9 baking pan with parchment paper or aluminum foil.
In a medium bowl, combine flour, baking soda, baking powder, spices, and salt. Set aside.
In the bowl of an electric mixer, combine the coconut oil and sugars. Beat on medium speed for 2 minutes. Add egg, vanilla, and maple syrup and mix on medium speed until well combined, 1-2 minutes. Turn the mixer to the lowest setting. Add in the flour mix. Stir until it is all incorporated. Remove the bowl from the mixer stand. Add the bananas and ¾ C of the nuts and chocolate chunks. Fold in with a spatula until it is mixed throughout.
Pour batter into prepared pan. Sprinkle the remaining nuts and chocolate on top of the cake. Top with coarse sugar (optional).
Bake in preheated oven for 25 minutes or until top springs back when gently pressed.