In a large bowl, whisk together the oat flour, almond flour, coconut sugar, baking powder, baking soda, cinnamon, and salt.
Add the mashed bananas, almond milk, melted coconut oil, and vanilla. Mix until well combined. The batter will be thick.
Pour the batter into a 10x7-inch baking dish and spread using a spoon to flatten. (I used this baking dish). Set aside.
In a small saucepan, warm the water over medium heat. Once warm, remove from heat and add the coconut sugar to the water. Whisk until the sugar is almost fully dissolved.
Slowly pour the sugar water over the pudding batter. I recommend pouring over the back of a spoon, this way you won't make holes in the batter and distribute it more evenly.
Bake for 25 minutes, or until the top looks cooked. Remove from heat and let cool 5-10 minutes. You will end up with a moist banana cake with a thick sauce at the bottom. Serve warm topped with vanilla ice cream.
This pudding cake will keep for up to 3 days covered in the refrigerator. To reheat: cover with foil and reheat in a 350°F preheated oven for 10 minutes.
*To mash bananas, peel them and place them on a deep plate. Use a fork to press down on the bananas. Alternatively, you can add them to a blender and blend on high speed until smooth.Baking 25 minutes yields a very moist, almost sticky cake with a generous sauce on the bottom (my favorite!), but if you want it less saucy and a bit less pudding-like, bake for 30 minutes.