Preheat your oven to 350°F (175°C). Grease and flour a 9x5 inch loaf pan or line it with parchment paper, leaving an overhang for easy removal.

In a large mixing bowl, add the ripe bananas and mash them with a fork or potato masher until they are mostly smooth. A few small lumps are perfectly fine.

To the mashed bananas, add the Greek yogurt, maple syrup, melted coconut oil, egg, and vanilla extract. Whisk everything together until the mixture is smooth and well combined.

Sprinkle the whole wheat pastry flour, baking soda, cinnamon, and salt directly over the wet ingredients in the bowl. Use a rubber spatula to gently fold the dry ingredients in until just combined. Do not overmix; a few streaks of flour are okay.

Pour the batter into the prepared loaf pan and spread it into an even layer. Bake for 50-60 minutes, or until a wooden skewer inserted into the center of the loaf comes out clean or with a few moist crumbs attached. If the top is browning too quickly, you can tent it loosely with foil for the last 10-15 minutes.

Place the pan on a wire rack and let the banana bread cool in the pan for at least 15 minutes. Then, use the parchment paper overhangs to lift the loaf out and let it cool completely on the wire rack before slicing. This prevents it from crumbling.