In a small bowl, use a fork to whisk together the flaxseed and water to make a flax egg. Set aside for 10-15 minutes.
Preheat the oven to 350° F and grease and line a standard loaf pan with parchment paper.
In a mixing bowl, whisk together the buckwheat flour, baking powder and baking soda.
In another bowl, use a wooden spoon to combine the melted vegan butter with the coconut sugar until smooth.
Stir in the flax egg, mashed banana and vanilla extract.
Stir in the coconut yogurt.
Sift in the flour mixture and stir to combine.
Add about half of the chocolate chips and gently fold in until evenly distributed.
Transfer the mixture to the loaf pan and sprinkle the rest of the chocolate chips on top.
Bake for 30-40 minutes. If you prefer the top less browned, you can cover it with foil after about 25 minutes of baking.
