Preheat the oven to 350 degrees F and grease a standard loaf pan (8 1/2 x 4 1/2 inches or 9 x 5 inches). I also like to line the pan with parchment paper for easy removal later.
Pour the soy milk into a glass measuring cup or bowl and stir in the ground flaxseeds with a fork. Let sit for a few minutes to thicken.
In a large bowl, mash the bananas with a fork until smooth. Scoop it into a measuring cup to make sure you have about 1 1/2 cups, then return to the bowl.
Stir the melted vegan butter into the bananas, then add the brown sugar and milk/flax mixture. Stir well with a large spoon until combined.
Add the flour and cocoa powder on top of the wet ingredients, then sprinkle the baking soda and salt on top. Stir gently until just combined, being careful not to over mix.
Gently fold in 3/4 cup of the chocolate chips, leaving the rest for the top.
Pour into the prepared pan and sprinkle the rest of the chocolate chips on top. Place in the center rack of the oven and bake for 50-60 minutes, or until a toothpick inserted in the center comes out clean.
Let it cool in the pan for about 15 minutes, then carefully transfer to a cooling rack. Let cool for at least 30 minutes if possible, as this will make it easier to slice. Serve and enjoy!