Preheat the oven to 350ºF. Line a loaf pan with parchment paper so the bread doesn’t stick, and set aside.
Add the bananas to a large bowl and mash until almost smooth (I leave a few little chunks behind to see & taste in the bread). Add the eggs, melted butter or coconut oil, and vanilla, and stir until just combined (don’t over-stir or the bread won’t rise well!)
In a separate bowl, mix the dry ingredients (almond flour, arrowroot, coconut sugar if using, baking soda, baking powder, cinnamon, nutmeg, and salt). Add to the bowl of wet ingredients, stirring just enough to combine - until you can’t see lumps of flour.
Pour the batter into your prepared loaf pan and transfer it to the oven. Bake for 50 minutes to 1 hour, or until golden brown and “set” in the middle. A toothpick inserted to the center should come out clean. Allow the bread to cool completely then remove from the pan, slice, and serve! Store leftovers in the refrigerator for your banana bread to last the longest.