Preheat oven to 350°.
Melt butter in a microwave-safe bowl. Set aside for 10-15 minutes to let it cool.
Add yogurt and then eggs to the cooled butter and whisk to evenly combine. Add sliced bananas to the wet mix and mash until you have a very smooth blend. I use a fork or a potato masher.
Whisk together flour(s), sugar, baking soda, and salt in a large mixing bowl.
Add the the wet stuff to the dry stuff and fold together until you can’t see dry stuff any more, but no longer to avoid tough batter. Finally, add in the nuts and raisins and fold to get an even distribution.
Use a rubber spatula to get every bit of the batter into a buttered, non-stick loaf pan. Bake for 60 minutes at 350°. Do the toothpick test or use your digital thermometer (195-200°) to see if it’s done. The idea is to get a lightly crispy crust and a soft, completely-baked interior. Don’t bake any longer than necessary or the bread will lose some of its signature moistness.
Remove pan from oven and set out to cool on a wire rack for 15 minutes. Invert the pan and catch the bread as it drops out. Using my recommended pan, well-buttered, should make this easy. Let the bread sit for an hour on the wire rack before slicing. Go read a book to cool your jets and try to keep impatient family members away from the goods. Slice and eat plain or with butter or cream cheese and jam, especially when the bread is fresh.
When bread is completely cool (if there's any left), wrap in foil and store in fridge for 3-4 days or cut it in half and freeze a portion for several months.