Preheat your oven to 350, and find a glass loaf pan.
Melt half a stick of butter (that's 4 tablespoons) and let it cool.
(If you're melting it in the microwave, keep a darn eye on it and stop it as soon as it melts, otherwise the solids will explode all over the inside of your appliance. It's gross.)
(Next, time, I will try this with coconut oil.)
Mash (or mix in your mixer) 3-5 ripe bananas. They should be super, super liquidy and make more than a cup of liquid banana goop. Mix in 1 cup sugar (I combined brown and white) and 1 egg. then that cooled melted butter (if its too far above about 80 degrees, it'll cook bits of egg.) Add a big swig of vanilla extract, and any likely-looking spices. I used quite a lot of Penzey's Pumpkin Pie spice. It was awesome.
Turn off the mixer once all that is combined. Now dump in 1.5 cups of rice flour (mine was 2/3 brown, 1/3 white), a scant tablespoon of baking soda, and a generous teaspoon of salt.
Turn the mixer on LOW and only mix it until everything is barely moistened. Large veins of dry baking soda or snowdrifts of flour are undesirable; however, lumps are fine.
Grease your loaf pan (with butter) and transfer the batter into it. It is heavy, thick and lumpy. It is brown. It does not look or pour like cake batter. It'll be okay. Seriously.
If you want to add walnuts (or black walnuts), I recommend sprinkling them on top. I have a firm 'no surprise nuts' policy, but there's actually a better reason. Having them on top allows the nuts to toast, which makes them taste lots better, and be crunchy. (It also moderates the distinctive but occasionally weird green note in good black walnuts. I think it's a perfect flavor for this bread, but can be overwhelming unless they're toasted.)
After putting the pan in the oven, lower the temp to 325. DO NOT open the oven for 45 minutes.
Begin checking at 45 minutes with the stab-with-a-butterknife method. The timing is quite changeable - could be done after 45 minutes, but occasionally takes more than an hour. I think it's because of the banana variable. When the butterknife finally comes out moderately clean - with actual moist crumbs stuck to it, rather than batter - it's done.
This came out moist, tasty, and with a good texture - springy but in no way rubbery. It looked nice, too, and the family ate it enthusiastically. Oddly, it did not have a very strong banana flavor - it was there, but not as banana-y as I would have expected.
This loaf took a long time to get done in the middle, and I worried that the ends would be overdone and hard or gummy - but they totally weren't. I was also worried that the middle would be gritty, but that's what I get for licking the knife - but, again, not at all. Good consistent texture and rise throughout the loaf. Deep carmelized sugar flavor.
Anyway, it was good.
I might add chocolate chips next time.
This is a rice flour adaptation of the wheat flour recipe I always use. (I happen to have noted, on the page of my recipe notebook, that my brother and I made it on July 15, 1996.) From Easy Basics for Good Cooking.