Those ripe bananas on the counter could become another banana loaf. But if what you’re craving is chocolate cake, use them for this instead.
This is a soft, moist chocolate banana cake with a tender cake crumb and plenty of cocoa. The banana brings sweetness, moisture and a gentle banana flavour, but chocolate still leads. In other words, it eats like chocolate cake with banana in it—not banana bread dressed up with cocoa.
No mixer required. Two bowls, a whisk, a spatula and one 9-inch square pan will do it. The one measurement worth being particular about is the banana: weigh 250g after peeling rather than relying on a banana count.
If banana rather than chocolate is what you want to taste first, our moist banana cake with cream cheese frosting takes that route instead.
Ready to bake? Jump straight to the recipe and method.
Table of Contents
- Chocolate Banana Cake Recipe
- A Few Ingredients That Matter
- Plain or with Ganache?
- Optional Chocolate Ganache
- Variations and Substitutions
- Troubleshooting
- Storage and Freezing
- Frequently Asked Questions
Quick Answer
For a moist chocolate banana cake that stays soft and cake-like, use 250g mashed ripe banana with 190g all-purpose flour and 50g natural cocoa. Bake it in a 9-inch (23cm) square pan at 175°C/350°F for about 35–40 minutes, beginning your first check around 35 minutes. It’s ready when the middle is set and a skewer brings up a few moist crumbs rather than wet batter.
Chocolate Banana Cake Recipe
Prep time: 20 minutes
Bake time: about 35–40 minutes; begin checking at 35 minutes
Cooling time: about 1 hour total
Pan: 9-inch (23cm) square cake pan
Oven: 175°C/350°F conventional or 160°C fan
Yield: 12–16 pieces
Ingredients
- 250g (about 1 cup plus 2 tablespoons) very ripe mashed banana, weighed after peeling
- 190g (about 1½ cups plus 1 tablespoon) all-purpose flour
- 50g (about ½ cup plus 1½ tablespoons) unsweetened natural cocoa powder
- 1 teaspoon baking powder
- ½ teaspoon baking soda
- ½ teaspoon fine salt
- 100g (½ cup packed) light or dark brown sugar
- 80g (about ⅓ cup plus 1 tablespoon) granulated sugar
- 100ml neutral oil, such as sunflower, canola or vegetable oil
- 2 large eggs
- 120g (½ cup) plain unsweetened yogurt
- 2 teaspoons vanilla extract
Optional: 85–100g (about ½ cup) dark or semisweet chocolate chips or chopped chocolate.
Weights are the reference measurements; cup amounts are approximate, especially for banana, flour and cocoa.
Method
- Heat the oven. Set it to 175°C/350°F conventional or 160°C fan. Lightly grease a 9-inch (23cm) square pan and line the base and two sides with baking paper, leaving enough overhang to lift the cake out later.
- Mash the bananas. Mash the peeled fruit until mostly smooth, then weigh out 250g. A few small, soft pieces are perfectly fine; there is no need to turn the banana into a completely smooth purée.
- Mix the dry ingredients. Whisk the flour, cocoa, baking powder, baking soda and salt together thoroughly. Break up any stubborn cocoa lumps while you’re there.
- Mix the wet ingredients. In a larger bowl, whisk the brown sugar, granulated sugar and oil until combined. Whisk in the eggs, then add the yogurt, vanilla and mashed banana. It may look a little uneven once the banana goes in. That’s normal.
Fold the Batter and Fill the Pan
- Make the batter. Add the dry ingredients to the wet mixture and fold with a spatula, scraping around the sides and across the bottom of the bowl. Stop as soon as the flour and cocoa disappear into the batter. It should be fairly thick and spreadable. Fold in the optional chocolate chips or chunks with the final few strokes.
Before moving the batter into the pan, look at how a spoonful falls back into the bowl. This is a useful final texture checkpoint, particularly when the ripeness of your bananas varies.
- Fill the pan. Scrape the batter into the prepared pan, ease it into the corners and level the top. Once it’s even, leave it alone.
Bake, Test and Cool
- Bake. Put the pan on the centre rack and bake for about 35–40 minutes, beginning your first check around 35 minutes. Don’t judge this dark cake by colour alone. The glossy look across the middle should disappear and the surface should look set rather than wet.
- Check for doneness. Insert a thin skewer into the middle. A few moist crumbs are enough; liquid batter means it needs a few more minutes. If the skewer is smeared with melted chocolate, test another spot before returning the cake to the oven. You may simply have tested a chocolate chip rather than the cake.
A dark streak on the skewer can be misleading when the batter contains chocolate pieces. Compare the examples below before deciding that the whole cake needs more oven time.
- Cool. Leave the cake in its pan for about 15 minutes, then lift it onto a rack. Let it cool before slicing, and cool it completely before adding ganache. The crumb settles as the cake cools and slices much more cleanly than it does straight from the oven.
What the Cooled Crumb Should Look Like
Once the cake has cooled, cut a square from near the centre. The exposed crumb tells you more about the result than the dark surface does: it should hold its shape without smearing, crumbling apart or looking unset.
If your finished cake looks wet, gummy or unusually heavy, the troubleshooting guide separates those problems and their likely causes.
A Few Ingredients That Matter
Don’t Count Bananas; Weigh Them
Use bananas that are soft, fragrant and generously speckled with brown. Very dark skins are fine as long as the fruit itself smells fresh and shows no mould or spoilage.
The recipe uses 250g banana after peeling. That’s more useful than telling you to use “three bananas,” because three small bananas and three enormous bananas are not remotely the same amount of fruit.
You don’t need to worry about being a few grams either side. The point is to avoid casually adding a great deal more banana than the recipe was built around. More fruit brings more moisture, and enough extra can make the cake heavier and push it closer to banana bread territory.
Frozen ripe bananas work too. Thaw them completely and keep the liquid they release. Mash the fruit and liquid together, then weigh 250g of the mixture.
Use Natural Unsweetened Cocoa
Use natural unsweetened cocoa here. Dutch-process cocoa has different acidity, so it isn’t a straight swap in this formula. Drinking chocolate isn’t a substitute either; it usually contains added sugar and much less cocoa.
If you’re curious about the chemistry, King Arthur Baking explains natural and Dutch-process cocoa in detail. For a chocolate cake without banana in the formula, see our classic moist chocolate cake.
Weigh the Flour if You Can
If you’re measuring the 190g flour by volume, spoon it into the cup and level the top instead of scooping straight from the bag. A heavily packed cup can add considerably more flour and leave the crumb heavier and drier. King Arthur Baking’s flour-measuring guide shows the method clearly.
This is one place where precision matters. Whether your walnuts later weigh 72g or 78g really doesn’t.
Plain or with Ganache?
Leave the cake plain and you get the simpler version: chocolate-banana squares that are easy to pick up and very much at home beside tea or coffee. A light dusting of cocoa or icing sugar is plenty if you want to dress the top without adding another layer.
Ganache changes the mood. It adds another hit of chocolate and a smooth, rich layer against the cake underneath, so the same square suddenly feels much more like dessert.
For some tang against the chocolate, our smooth cream cheese frosting is another option. Ganache, though, keeps this particular cake firmly in chocolate territory.
Optional Chocolate Ganache
- 150g dark or semisweet chocolate, finely chopped
- 120ml (½ cup) heavy or whipping cream
- Put the chopped chocolate in a heatproof bowl.
- Heat the cream until steaming and just beginning to simmer around the edges.
- Pour it over the chocolate and leave it alone for 2 minutes.
- Stir slowly from the centre outwards. It may look streaky at first; keep going gently and it will come together.
- Let the ganache cool until thick enough to spread without running straight off the cake.
- Spread it over the completely cooled cake and give it time to settle before slicing.
If the ganache is still running off the spoon, give it more time to cool. If it has gone firmer than you wanted, warm it very gently until it loosens again.
Variations and Substitutions
Bake the basic version once before changing half the bowl.
- Chocolate chips or chunks: Fold in 85–100g for pockets of melted chocolate through the crumb. Dark or semisweet chocolate keeps the sweetness in check.
- Toasted walnuts: Add about 75g, roughly chopped. They bring crunch to an otherwise tender cake and work naturally with both banana and chocolate.
- Espresso powder: Add 1 teaspoon with the dry ingredients. At that amount it deepens the cocoa flavour without making the cake taste obviously of coffee.
Some changes go beyond a casual substitution. Replacing all the oil with butter, cutting the sugar dramatically, removing the eggs or swapping the wheat flour for almond or coconut flour changes the structure of the cake. Those need more than a straight one-for-one exchange.
Troubleshooting Your Chocolate Banana Cake
Dense, gummy and raw are three different problems. Before changing the recipe next time, have a look at what actually happened to this cake.
The Middle Is Still Wet or Raw
Wet batter on the skewer usually means the simplest thing: it needs longer in the oven. Loosely cover the top with foil if it is already dark enough, then continue baking at the same temperature and check again after a few minutes.
When this happens repeatedly, check the oven temperature and pan size. A smaller pan—or any setup that leaves the batter in a deeper layer—will take longer for the middle to bake through.
The Crumb Is Gummy or Pasty
A gummy cake isn’t always an underbaked one. Too much banana is one possibility, particularly when bananas were measured by number instead of weight. With frozen fruit, remember that the thawed banana and its released liquid together should total about 250g.
Also give the cake time to cool before deciding something went wrong. The crumb is softer and more delicate while the cake is hot, so its final texture is easier to judge once it has cooled.
The Cake Is Dense but Fully Baked
A tight, heavy crumb points somewhere else. Too much flour, old or mismeasured leavening, or a lot of mixing after the flour goes in can all make the cake denser than intended. Weigh the flour if possible and stop folding once the batter is combined.
It Rose and Then Sank
A little settling as the cake cools is normal. A deep dip through the middle is different and often means the structure wasn’t quite set when the cake came out. Too much baking powder or soda can also make a cake rise quickly and then fall back.
The Edges Are Done but the Middle Isn’t
Loosely cover the top with foil and keep baking. The foil slows further browning while the middle catches up. If it happens repeatedly, check the pan and oven: a dark pan, smaller pan or oven running hot can cook the outside faster.
The Cake Turned Out Dry
Too much flour and too much oven time are the first places to look. Weigh the flour if you can and remember that a few moist crumbs on the skewer are enough—you don’t need to bake until it comes out bone-dry.
And don’t throw away an already-dry cake. Ganache, softly whipped cream or vanilla ice cream can make those slices much nicer to eat.
There Are Large Holes or Bitter Spots
A bitter or soapy patch is a good reason to suspect a pocket of baking soda. Large tunnels can also come from uneven mixing or too much leavener. Give the dry ingredients a proper whisk at the beginning so the small quantities of baking powder and soda don’t sit in one part of the batter.
Storage and Freezing
Let the cake cool before covering it. Wrap it while it’s still steaming and that moisture has nowhere to go except back onto the surface.
- Room temperature: Keep the plain cake tightly covered for up to 2 days in a cool room. In a hot or humid kitchen, refrigerate it sooner.
- Refrigerator: Keep it covered for up to 5 days. Chilled cake will be firmer, particularly under ganache, so give a slice some time at room temperature before eating if you prefer it softer.
- Freezer: Wrap cooled individual slices well and freeze for up to 3 months. Thaw them while still wrapped so condensation collects on the wrapping rather than directly on the cake.
Frequently Asked Questions
Can I Make Chocolate Banana Cake a Day Ahead?
Yes. Bake it, cool it and keep it well covered. You can leave it plain or add the ganache once the cake is completely cool. That makes it easy to bake the day before you plan to serve it.
Can I Use It as a Birthday Cake?
Yes. It works well as a simple single-layer celebration cake, especially with ganache over the top. Add candles, chocolate curls, sprinkles or chopped toasted nuts and leave the complicated decorating to another birthday.
Can I Double the Recipe?
Yes, but don’t put twice the batter into the same 9-inch pan. Divide a double batch between two pans instead. When both are baking together, leave some space around them for air to circulate and expect the exact baking time to vary with your oven.
One Last Slice
There are days when ripe bananas call for banana bread. And there are days when you look at the same bananas and would much rather have chocolate cake. This is for the second kind of day.
And if what you wanted all along was warm chocolate with a molten middle, save the bananas for breakfast and make our chocolate lava cakes instead.
Bake this one? Tell us what you did—your pan, approximate bake time, any substitutions and, most useful of all, how the crumb turned out. Those details can help the next baker far more than a simple “loved it.”
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