1) Add chia seeds to apple juice. Set aside while the seeds absorb the juice and thicken. Preheat the oven to 350 degrees and grease two pans.
2) Stir flour, baking powder and salt together, and set aside. Beat eggs and then add pure maple syrup and melted butter. Mix well. Add banana, vanilla and chia seed mixture. Add baking soda to Greek yogurt (or buttermilk) and mix, then add this mixture to the wet ingredients. Mix well and add flour mixture (and nuts if you are using ground rather than chopped). Avoid over mixing.
3) Fold in chopped nuts (optional). Pour into greased loaf pans and bake for about 45 minutes or until a toothpick comes out clean, but watch carefully to not over cook. Enjoy!