For the best, most flavorful bread, the bananas need to be ripe — overripe, brown and speckled is even better. Nuts are completely optional for this. We love the bread both ways, but do enjoy the extra crunch from a handful of walnuts or pecans. A note on pan size: We use a 8 1/2- by 4 1/2-inch loaf pan; if you only have a 9- by 5-inch pan, start checking for doneness 5 to 10 minutes earlier.
1 1/2 cups (195 grams) all-purpose flour
1 teaspoon baking soda
1/2 teaspoon kosher salt
3/4 teaspoon ground cinnamon
3 medium bananas, heavily speckled or even black bananas are best (about 1 1/2 cups mashed)
8 tablespoons (115 grams or 1 stick) unsalted butter, melted and cooled
3/4 cup (150 grams) packed light brown sugar
2 large eggs, lightly beaten
1 teaspoon vanilla extract
1/2 cup (50 grams) walnuts or pecans, toasted and chopped, optional
Center a rack in the oven and heat to 350 degrees F. Butter and flour an 8 1/2-inch-by-4 1/2-inch loaf pan. Place the pan on an insulated baking sheet or on two regular baking sheets stacked on top of the other.
Whisk the flour, baking soda, salt and cinnamon together, set aside. In the bottom of a medium bowl, mash bananas into a chunky paste. Whisk the melted butter, brown sugar, eggs and vanilla into the bananas until blended.
Switch to a large rubber spatula. Scrape the sides and bottom of the bowl then add the dry ingredients in 3 parts, stirring gently until they disappear and the batter is smooth. Stir in nuts.
Pour batter into the pan and smooth the top. Bake 55 to 75 minutes, or until a knife inserted into the center of the bread comes out clean. After 30 minutes in the oven, check the bread for color. If it looks like it is browning too quickly, loosely cover with aluminum foil.
When the bread is done, transfer it, in the pan, to a wire rack to cool for 5 minutes. Unmold the bread and place right side up on the rack. Cool completely.