Banana-Chocolate Marble Bread
- Unsalted butter for pan
- 1 1/2 cups plus 2 tablespoons unbleached all-purpose flour plus more for pan
- 1 teaspoon baking soda
- 1/4 teaspoon cinnamon
- 1/4 teaspoon kosher salt
- 1 cup plus 2 tablespoons sugar
- 2 large eggs
- 1/2 cup vegetable oil
- 1 1/2 cups coarsely mashed very ripe bananas (3 large)
- 2 tablespoons sour cream
- 1 teaspoon pure vanilla extract
- 1/4 cup Dutch process cocoa powder
- 1/4 cup boiling water
Preheat oven to 350°F with rack in middle.
Generously butter a (9- by 5- by 3-inch) metal loaf pan, then dust with flour, knocking out excess.
In a bowl, whisk together flour, baking soda, cinnamon and salt.
In bowl of electric mixer fitted with the paddle attachment, beat sugar and eggs on medium-high speed until very thick and pale, about 10 minutes.
Reduce speed to low and add oil in a slow stream, mixing until incorporated, then mix in bananas, sour cream, and vanilla.
Remove bowl from mixer and fold in flour mixture.
Transfer one-third of the batter to a medium bowl; set aside.
Spoon the remaining batter into prepared pan.
In a small bowl, whisk together cocoa powder and the boiling water until smooth; stir cocoa mixture into reserved batter until well combined.
Spoon chocolate batter over batter in pan to cover, then, to create marbling, run a table knife through the batters in a swirling motion, swirling batter from underneath to top and vice versa (do not over-swirl or the batters will combine and you won’t see the marbling pattern).
Bake for 50 minutes, then tent loaf with foil and continue to bake until a wooden pick or skewer comes out clean, 15 to 25 minutes more.
Cool loaf in pan on wire rack for 10 minutes, then turn out onto rack. Turn loaf right side up and cool complete