Marbled Chocolate Banana Bread with Mini Chocolate Chips

This marbled chocolate banana bread is moist and soft, with swirls of plain banana batter and chocolate banana batter. It's made in one bowl with no mixer. Mini chocolate chips go inside the batter and on top.

Marbling is easy to overdo, so a few gentle passes with a knife is enough here. If you want more practice, this pumpkin marble cake uses the same figure-8 swirl method with pumpkin and chocolate batter.

Ingredients

Ripe bananas: Use bananas with lots of brown spots. They add sweetness and moisture, and they mash smoothly. Bananas that are only yellow will give you a drier, blander loaf.

Unsalted butter: Melted butter keeps this a one-bowl recipe. It also makes the crumb soft and rich.

Granulated sugar: The sugar sweetens the bread and helps keep it moist.

Egg: One room-temperature egg binds the batter. It blends in more easily than a cold one.

Baking soda: Baking soda lifts the loaf. It also reacts with the acidity in the bananas.

Cocoa powder and milk: Cocoa turns one third of the batter into chocolate. The milk loosens it, because cocoa makes the batter thicker.

Mini chocolate chips: Minis spread more evenly through the batter and melt into small pockets. They also look neater on top than regular chips.

How to Make Marbled Chocolate Banana Bread

Mash the bananas in a large bowl until mostly smooth.

Whisk in the melted butter, sugar, egg, and vanilla until glossy.

Add the flour, baking soda, and salt. Stir with a spatula just until no dry streaks remain.

Scoop about ⅓ of the batter (about 1⅓ cups) into a separate bowl. Stir in the cocoa powder and milk until smooth, then fold in ¼ cup mini chocolate chips.

Spoon dollops of plain and chocolate batter into the prepared pan, alternating between them.

Drag a knife or skewer through the batter 3 or 4 times to create the marbled effect. Stop early, because more passes blend the colors.

Sprinkle the remaining ¼ cup mini chocolate chips on top and bake.

Cool the loaf in the pan for 15-20 minutes. Lift it out with the parchment and cool it completely on a wire rack before slicing.

Expert Tips

• Use very ripe bananas with plenty of brown spots. This gives the loaf the most sweetness and moisture.
• Do not overmix the batter. Stirring too much makes the loaf dense instead of tender.
• Swirl gently. A few passes with a knife is enough. More passes blend the batters into one muddy color.
• Add the top chocolate chips right before baking so they stay visible and don't sink.
• I use mini chips because they spread evenly and melt into small pockets. Regular chips melt too much to the bottom of the loaf for me.
• It's normal for the chocolate batter to look thick. It loosens as you fold in the chips.
• I baked this in a 9x5-inch metal pan. Start checking for doneness at 55 minutes. A toothpick should come out clean or with a few moist crumbs. 
• Let the loaf cool before slicing. A warm loaf crumbles, and the swirl looks cleaner on a cooled one.

Storage

• Room temperature: Wrap the loaf tightly and keep it up to 3 days.
• Refrigerator: Keep it wrapped up to 5 days.
• Reheat: Microwave a slice for 15-20 seconds to bring back a fresh, soft texture.
• Freezer: Wrap slices individually and freeze up to 2 months.

More banana bread and banana baking

• Maple-Glazed Banana Pecan Muffins: muffins with a maple glaze, for a faster bake than a loaf.
• Double Chocolate Banana Bread: a chocolate loaf made with cocoa and chocolate chips, for readers who want more chocolate than a swirl.
• Moist Strawberry Banana Bread: a fruit version of the same loaf.
• Green Banana Flour Bread (No Ripe Bananas Required): a gluten-free loaf made with quinoa flour, good for when you don't have spotted bananas.