Grease a 9x5 loaf pan or line it with parchment paper.
In a stand mixer or large mixing bowl, prepare the flax eggs by whisking together the ground flaxseed and room temperature water. Set aside for 10 minutes, or until the texture is gelatinous like egg whites.
After 10 minutes, add in the mashed banana, room temperature maple syrup, coconut oil, vanilla extract and beat to combine with whisk attachment on stand mixer or handheld whisk. If you do not use room temperature maple syrup, the coconut oil will harden and change the texture of the loaf (it gets incredibly oily).
Add in the all purpose flour, baking soda, cinnamon and nutmeg. Using the lowest setting on stand mixer or with handheld spatula, fold dry ingredients into wet until just combined.
Sprinkle in the kosher salt and chocolate chunks or chocolate chips and fold into batter with a spatula (do not use stand mixer for this).
Pour mixture into loaf pan and bake for 45-60 minutes, or until toothpick comes out clean in center of loaf. I like to tent the banana bread with tin foil half way through to prevent over browning.
Allow loaf to cool in pan for 10 minutes before moving it to a baking rack to cool completely.
Storage: Store bread in an airtight container at room temperature for up to 5 days. I do not recommend refrigerating this bread - it makes it very dense.
Notes
If you are out of banana or do not have enough, you can substitute unsweetened apple sauce.
If you do not want to use chocolate chips, substitute chopped pecans or walnuts instead or simply omit.
To make gluten free: Swap the all purpose flour for Bob's Red Mill All Purpose Baking Flour and bake for 5-10 minutes longer. This recipe has not been tested with another brand of gluten free flour so I cannot guarantee results. Do not use almond flour, coconut flour or oat flour as they are very different.
To make muffins: Bake at 350 for 20-25 minutes, or until toothpick comes out clean. This recipe should yield about 12 muffins.
Mini muffins have not been tested, and would require a shorter bake time.
Do not bake this loaf in a glass loaf pan. Glass operates very differently from aluminum and will not cook this loaf properly.