Preheat your oven to 350°F and line a loaf pan with parchment paper.
In a large bowl, whisk mashed bananas, eggs, maple syrup, yogurt, butter, and vanilla.
In a separate bowl, mix flour, baking powder, baking soda, cinnamon, and salt.
Stir the dry ingredients into the wet just until combined — no overmixing, we want soft.
Gently fold in the blueberries (if using frozen, toss them in a little flour first to avoid sinking).
Pour into your prepared loaf pan. Press a few extra blueberries on top for good measure.
For the crumble: Use a fork or your fingertips to work the ingredients together until it looks like wet sand with buttery clumps. Sprinkle it all over the top.
Bake for 50–60 minutes. Start checking around the 50-minute mark — a toothpick should come out clean or with just a few moist crumbs.
Let cool in the pan for 10 minutes before transferring to a wire rack. Slice and live your best cozy life.