Preheat the oven to 350°F (180°C). Line an oiled loaf pan with parchment paper.
In a large mixing bowl, mash the bananas and sweet potato together.
Add the maple syrup, melted butter, egg, and 1 tbsp vanilla. Whisk until well combined.
Sift in the flour, baking soda, and salt. Fold until just combined. A few clumps of flour are fine; avoid overmixing the batter.
Top with flaky sea salt or optional toppings and bake for 40-45 minutes, until a toothpick comes out clean.
Allow to cool for 10 minutes, slice, and serve.
