This Marble Chocolate Banana Bread is as lovely to look at as it is delicious. A classic banana bread batter is split, with cocoa added to one half and a touch more flour to the other, then the two batters are layered and gently swirled to create a beautiful marbled loaf. The result is rich, incredibly tender bread packed with banana and chocolate flavor.
How to achieve the Marble Effect
The marbling is simple and striking. Make one batch of banana bread batter, divide it into two bowls, add sifted cocoa powder to one bowl and the remaining flour to the other. Spoon alternating scoops of chocolate and plain batter into the prepared loaf pan, then use a long skewer to make a few gentle swirls — just enough to create the marbled pattern without overblending. That’s all it takes for an evenly patterned Marble Chocolate Banana Bread.
How to make the Marble Chocolate Banana Bread
1. Mix the wet ingredients: In a large bowl combine melted butter, oil, light brown sugar, eggs, mashed overripe bananas, full-fat sour cream and vanilla. Beat until very smooth.
2. Whisk the dry ingredients: In a separate bowl whisk together 1 cup (120g) flour, baking soda and salt.
3. Combine wet and dry: Add the dry mixture to the wet ingredients and mix until just combined — don’t overmix.
4. Divide the batter: Split the batter evenly between two bowls.
5. Add cocoa and extra flour: Stir the cocoa powder into one bowl until smooth. Add the remaining 1/4 cup flour to the other bowl and mix until just combined.
6. Alternate batters: Spoon alternating scoops of chocolate and plain batter into a prepared 9×5″ loaf pan. When the pan is filled, lightly swirl with a bamboo skewer to create the marble pattern.
7. Bake: Bake at 350°F (175°C) until a toothpick inserted in the center comes out clean, about 55–60 minutes. Cool completely before slicing.
How ripe should the bananas be?
Use very ripe bananas — the skins should be heavily speckled or nearly black. Overripe bananas are sweeter and much softer, which improves both flavor and texture. As bananas ripen, starches convert to sugars, making them naturally sweeter and easier to mash for smooth batter.
If your bananas aren’t ripe enough, place them in a paper bag at room temperature to speed ripening by a day or two. Sealing them in the bag traps ethylene gas and accelerates the process. Freezing unripe bananas will halt ripening, and baking bananas to blacken the peel changes texture without increasing sweetness, so those methods won’t produce the same results.
Smooth bananas for a smooth texture
For an even, uniform crumb, mash the bananas to a very smooth consistency before adding them to the batter. This prevents banana chunks in the finished loaf and yields a finer, more tender texture.
Get the Recipe:
Marble Chocolate Banana Bread
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Ingredients
- 1/4 cup Unsalted Butter, melted
- 1/4 cup Vegetable Oil, such as canola or walnut oil
- 1 cup Light Brown Sugar
- 2 Eggs
- 3 Overripe Bananas, mashed smooth
- 1/2 cup Full-Fat Sour Cream
- 1 tsp Vanilla
- 1 1/4 cups (150g) All Purpose Flour, divided, measured correctly †
- 1 tsp Baking Soda
- 1/2 tsp Salt
- 1/4 cup Dutch-processed Cocoa Powder, sifted
Instructions
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Preheat the oven to 350°F (175°C). Prepare a 9×5” loaf pan with oil and parchment. In a large bowl beat the melted butter, oil, brown sugar, eggs, mashed bananas, sour cream, and vanilla until smooth.
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In a separate bowl whisk together 1 cup (120g) flour, baking soda, and salt. Add the dry mixture to the wet ingredients and mix until just combined. Avoid overmixing for a tender crumb.
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Divide the batter into two bowls. Stir the cocoa powder into one bowl until smooth. Add the remaining 1/4 cup flour to the other bowl and mix until just combined.
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Alternate spooning chocolate and plain batter into the prepared loaf pan. Once filled, use a skewer to swirl lightly and create the marble design.
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Bake for about 55–60 minutes, or until a toothpick inserted in the center comes out clean. Cool completely on a wire rack before slicing.