Ingredients

6 ounces bittersweet chocolate, chopped for melting
1 1/2 cups all-purpose flour
3/4 teaspoon baking soda
1/4 teaspoon baking powder
1/4 teaspoon ground cinnamon
Pinch ground cloves
1 teaspoon pure vanilla extract
3 cups ripe bananas, diced (about 4 bananas)
1/3 cup buttermilk, at room temperature
1/2 cup (1 stick) unsalted butter, softened
1 cup sugar

2 tablespoons vegetable oil
1 large egg, at room temperature

Instructions

Position a rack in the
center of the oven and preheat to 350 degrees F. Butter and flour a 9-by-5-by-3-inch loaf
pan.

Put the chocolate in a heatproof bowl. Bring a saucepan filled with an inch or so of water
to a very slow simmer; set the bowl on the pan (without touching the water). Stir
occasionally until melted and smooth. Keep warm.

Whisk the flour, baking soda, baking powder, cinnamon, and cloves in a medium bowl. Stir
the vanilla and half the bananas into the buttermilk.

Beat the butter and sugar in a large bowl, with an electric mixer on medium-high speed
until light and fluffy, about 4 minutes. While mixing, drizzle in the oil and beat until
incorporated. Beat in the egg.

While mixing slowly add the flour mixture to the butter in 3 additions, alternating with
the buttermilk mixture in 2 parts, beginning and ending with the flour. (Scrape the sides
of the bowl between additions, if needed). Fold in the remaining bananas. Gently swirl the
melted chocolate into the batter so that it has a marbled effect. Scoop the batter into
the prepared pan. Bake until a toothpick inserted in the center comes out clean, about 50
minutes. Cool in the pan on a rack before unmolding and slicing.