From The New Best Recipe

2 cups (9 oz) unbleached all-purpose flour
3/4 cup (5 1/4 oz) sugar
3/4 tsp baking soda
1/2 tsp salt
3 very ripe, soft, darkly speckled large bananas, mashed well (about 1 1/2 cups)
1/4 cup plain yogurt
2 large eggs, beaten lightly
6 tbsp (3/4 stick) unsalted butter, melted and cooled
1 tsp vanilla extract

Adjust oven rack to lower-middle position and heat the oven to 350°F. Grease and flour the bottom and sides of a nonstick loaf pan, or just the bottom of a regular loaf pan. (I use an 8"x4" pan although the recipe suggests a 9"x5" pan. Bake it about 10 minutes longer if using the smaller size pan.)

Whisk the flour, sugar, baking soda, and salt together in a large bowl; set aside.

Mix the mashed bananas, yogurt, eggs, butter, and vanilla with a wooden spoon in a medium bowl. Lightly fold the banana mixture into the dry ingredients with a rubber spatula until just combined and the batter looks thick and chunky. Scrape the batter in the prepared pan.

Bake until the loaf is golden brown and a toothpick inserted in the center comes out clean, about 55 minutes (65 minutes for a smaller pan). Cool in pan for 5 minutes, then transfer to a wire rack. Serve warm or at room temperature. (The bread can be wrapped with plastic wrap and stored at room temperature for up to 3 days.)