Preheat oven to 350F
Grease 8x4" loaf pan (or 9x5 and reduce the baking time). If the pan isn't very non-stick, just use parchment paper (it also makes for easier removal in general).
Grind the chia seed in a coffee grinder or food processor. Transfer to a bowl and stir in the water. Set aside.
In a large bowl, whisk together the almond flour, sweetener, protein powder, coconut flour, baking powder and salt.
Stir in the eggs, melted butter, chia seed mixture, banana extract, and vanilla extract, until thoroughly combined. Stir in the water to thin the mixture to a scoopable consistency. If it's still very thick, add more water, 1 tablespoon at a time.
Stir in the chocolate chips, if using, saving a few for the top of the bread. Spread the batter in the prepared pan and sprinkle the top with the remaining chocolate chips.
Bake 60 to 75 minutes or until golden brown and a tester inserted in the center comes out clean. Let cool in pan 20 minutes, then run a sharp knife around the edges to loosen. Continue to let it sit in the pan until cool, about 20 minutes more.