Adjust oven rack to lower middle position and heat oven to 350 degrees. Grease bottom of 9x5-inch loaf pan. Grease and flour a 9x5-inch loaf pan if using nonstick bakeware.
Combine flour, sugar, baking soda, salt, and toasted walnuts in large bowl; set aside.
2 cups unbleached all-purpose flour, ¾ cup granulated sugar, ¾ teaspoon baking soda, ½ teaspoon table salt, 1 ¼ cups toasted walnuts,
Mix mashed bananas, yogurt, eggs, butter, and vanilla with wooden spoon in medium bowl.
3 very ripe bananas,, ¼ cup plain yogurt, 2 large eggs, 6 Tablespoons butter,, 1 teaspoon vanilla extract
Gently fold banana mixture into dry ingredients with rubber spatula until just combined to keep the loaf moist and tender. Scrape batter into prepared loaf pan.
To help minimize a crack that can result in the bread, using a rubber spatula, create a line or well that runs the length of the pan.
Bake until loaf is golden brown and toothpick inserted in center comes out clean, 50-55 minutes. Cool in pan for 5 minutes, then transfer to wire rack. Serve warm or at room temperature.