From America's Test Kitchen episode: Coffee Break Sweets.
Makes one 9-inch loaf
Be sure to use very ripe, heavily speckled (or even black) bananas in this recipe. This recipe can be made using 5 thawed frozen bananas; since they release a lot of liquid naturally, they can bypass the microwaving in step 2 and go directly into the fine-mesh strainer. Do not use a thawed frozen banana in step 4; it will be too soft to slice. Instead, simply sprinkle the top of the loaf with sugar. The test kitchen’s preferred loaf pan measures 8½ by 4½ inches; if you use a 9 by 5-inch loaf pan, start checking for doneness five minutes earlier than advised in the recipe. The texture is best when the loaf is eaten fresh, but it can be stored (cool completely first), covered tightly with plastic wrap, for up to 3 days.
1. Adjust oven rack to middle position and heat oven to 350 degrees. Spray 8½ by 4½-inch loaf pan with nonstick cooking spray. Whisk flour, baking soda, and salt together in large bowl.
2. Place 5 bananas in microwave-safe bowl; cover with plastic wrap and cut several steam vents in plastic with paring knife. Microwave on high power until bananas are soft and have released liquid, about 5 minutes. Transfer bananas to fine-mesh strainer placed over medium bowl and allow to drain, stirring occasionally, 15 minutes (you should have ½ to ¾ cup liquid).
3. Transfer liquid to medium saucepan and cook over medium-high heat until reduced to ¼ cup, about 5 minutes. Remove pan from heat, stir reduced liquid into bananas, and mash with potato masher until fairly smooth. Whisk in butter, eggs, brown sugar, and vanilla.
4. Pour banana mixture into flour mixture and stir until just combined with some streaks of flour remaining. Gently fold in walnuts, if using. Scrape batter into prepared pan. Slice remaining banana diagonally into ¼-inch-thick slices. Shingle banana slices on top of either side of loaf, leaving 1½-inch-wide space down center to ensure even rise. Sprinkle granulated sugar evenly over loaf.
5. Bake until toothpick inserted in center of loaf comes out clean, 55 to 75 minutes. Cool bread in pan on wire rack 15 minutes, then remove loaf from pan and continue to cool on wire rack. Serve warm or at room temperature.
Don’t even think of making banana bread with anything less than very ripe, heavily speckled fruit—unless you’re fine with a bland loaf. As bananas ripen, their starch converts to sugar at an exponential rate. In lab tests, we found heavily speckled bananas had nearly three times the amount of fructose (the sweetest of the sugars in fruit) than less spotty bananas. (The exact percentage will vary from fruit to fruit.) But the impact of ripeness only goes so far: We found little difference in sweetness between loaves baked with completely black bananas and those made with heavily speckled ones.
TOO SOON
1.8% FRUCTOSE
A lightly speckled banana has only a little fructose, the sweetest sugar in fruit.
JUST RIGHT
5.3% FRUCTOSE
A heavily speckled banana has a lot more fructose.
Typical banana bread contains just three pieces of fruit. Here’s how we upped the number to five without turning the loaf into pudding.
1. EXTRACT JUICE
Microwaving ripe bananas for 5 minutes causes them to release “juice.”
2. STRAIN IT OUT
After straining the bananas, you should have 1/2 to 3/4 cup of liquid to work with.
3. REDUCE THE JUICE
Reducing the banana liquid yields a concentrated liquor, intensifying flavor without making the loaf wet.
Layering thin banana slices on either side of the loaf adds even more banana flavor to our bread (and brings the total number of bananas in the recipe to six). To ensure an even rise, leave a 1½-inch-wide space down the center.