Preheat the oven to 350°F. Spray 2 (8-inch) round springform cake pans with cooking spray.
In a small bowl, prepare the flax eggs by whisking together the ground flax and water. Set aside for at least 10 minutes.
In a small bowl or measuring cup, mix the coconut milk and vinegar. Whisk and set aside.
In a large bowl or stand mixer, mix the almond flour, brown rice or white rice flour, coconut sugar, tapioca flour, baking powder, baking soda, and salt. Stir to blend.
Transfer the coconut milk and vinegar mixture to a high-speed blender or food processor. Add the flax eggs, bananas, peanut butter, coconut nectar or maple syrup, and vanilla extract. Blend until creamy. You can also combine everything in a medium bowl and whisk by hand (just make sure the peanut butter is really creamy!).
Pour the wet ingredients into the bowl with the flour mixture, and beat until a batter is formed. Fold in the chocolate chips.
Evenly distribute the batter between the prepared cake pans. Bake for 30 to 35 minutes until a toothpick comes out clean or the internal temperature reaches between 200° and 205°F. Allow the cakes to completely cool in the cake pans for about 2 hours.