Modifications for high altitude baking: halve the amount of baking soda. That’s it!
Other modifications: no walnuts, substituted sour cream with Chobani Less Sugar Madagascar Vanilla Greek Yogurt (bc that’s all I had in the fridge), mashed bananas instead of sliced. In the future I’d halve the amount of sugar just to see, and esp if using yogurt that already has sugar.
I had previously altered the recipe for high altitude baking and it came out cake-like. Decided to try again with fantastic results. Forgot to account for the added sugar in the yogurt so it is pretty sweet. Next time I will cut the sugar by half or more and see how it tastes. Baked for one hour, very moist!