1½ cups (210 grams) unbleached all-purpose flour
1 teaspoon baking soda
¼ teaspoon ground cinnamon
½ teaspoon kosher salt
1 cup plus 2 tablespoons (230 grams) sugar
½ cup (100 grams) canola oil
3½ very ripe, medium bananas, peeled and mashed (1½ cups, about 340 grams)
2 tablespoons crème fraîche or sour cream
1 teaspoon vanilla extract
¾ cup (75 grams) walnut halves, toasted and chopped
Position a rack in the center of the oven and heat the oven to 325ºF. Butter a 9-by-5-inch loaf pan.
In a bowl, sift together the flour, baking soda, cinnamon, and salt. Set aside.
Using a stand mixer fitted with the whip attachment, beat together the sugar and eggs on medium speed for about 5 minutes, or until light and fluffy. (If you use a handheld mixer, this same step will take about 8 minutes.)
On low speed, slowly drizzle in the oil. Don't pour the oil in all at once. Add it slowly so it has time to incorporate into the eggs and doesn't deflate the air you have just beaten into the batter. Adding it should take about 1 minute. Add the bananas, crème fraîche, and vanilla and continue to mix on low speed just until combined.
Using a rubber spatula, fold in the flour mixture and the nuts just until thoroughly combined. No flour streaks should be visible and the nuts should be evenly distributed. Pour the batter into the prepared loaf pan and smooth the top.
Bake for 1 to 1¼ hours, or until golden brown on top and the center springs back when you press it. If your finger sinks when you poke the bread, it needs to bake a little longer. Let cool in the pan on a wire rack for at least 30 minutes, and then pop it out of the pan to finish cooling.
The bread can be stored tightly wrapped in plastic wrap at room temperature for up to 3 days. Or, it can be well wrapped in plastic wrap and frozen for up to 2 weeks; thaw overnight at room temperature for serving.