Low Temperature Banana Bread is based on a banana bread from The Fairmont Hotel. I've always baked this at 275, but I recently tested it at 300 and it still browns and tastes just as good.
Preheat oven to 275 degrees F. Grease a 9x5 inch loaf pan, line with parchment paper and grease the parchment. Dust with flour. This is important, because the loaf is rather sticky!
In a blender, puree the bananas, sugar and baking soda.
Empty banana mixture into a mixing bowl. Mix in the eggs and the flour alternately, stirring until well blended.
Mix in the oil, buttermilk and salt, beating with a spoon until blended and smooth. Add the vanilla (if using) and the nuts.
Pour batter into prepared loaf pan and bake for 2.5 hours (though check for doneness at 2). Let cool completely, then carefully remove from the pan. If baking at 300, check at 1 .5 hours.
Internal temperature of banana bread should be around 205 so if you are not sure you can stick a probe in it to test.
Notes
The amount of baking soda seems like a lot, but it's what the recipe calls for and it's probably what creates the dark brown color. Update: I've reduced the baking soda to 2 teaspoons and the bread still gets pretty brown. Make sure to really grease and flour the pan well, as this bread is sticky! I used foil and nonstick spray, and still had some stickiness.