This chocolate marble banana Bundt cake is based off of this banana cake recipe. It’s a reader favorite and loved recipe because the cake is always moist, buttery, and full of banana flavor. Here we’re baking it in a Bundt pan and swirling it with real chocolate ganache so each bite has a delicious fudge-like ripple. We’ll have extra chocolate ganache for the topping, too!
Chocolate Marble Banana Bundt Cake Details
- Flavor: This chocolate marble banana Bundt cake starts with 1 and 1/2 cups of mashed banana, so you know there’s great flavor right from the get-go. It’s also buttery with notes of cinnamon, brown sugar, and vanilla too. And I’ll teach you how to swirl the ganache in such a way that literally every bite has dark chocolate as well!
- Texture: Because they’re so thick and essentially weigh themselves down, Bundt cakes are always denser than layer or sheet cakes. This is certainly a heavier cake, but it isn’t quite as dense as pound cake. It’s wonderfully moist and soft like banana bread, especially if you avoid over-baking.
- Ease: The prep consists of two main components: making the cake batter and making the ganache. Both are very simple, but the success of the recipe depends on timing. The ganache used for the swirl must cool for about 30 minutes prior to using otherwise it’s too thin. I recommend making the ganache first because by the time you’re finished the cake batter and the oven’s preheated, the ganache will be ready. You’ll use half of the ganache inside the cake, then save the rest for the topping.
What you’ll love most about this chocolate marble banana Bundt cake is that it’s swirled with real chocolate ganache and not chocolate flavored cake batter. I wanted the chocolate portion to be more like the chocolate swirl in fudge ripple ice cream and less like chocolate cake. Make sense? The best part is if you warm your slice back up in the microwave, the chocolate inside gets all melty like hot fudge sauce.
Swirled with Chocolate Ganache
Do you remember how to make chocolate ganache? I have an entire chocolate ganache tutorial page if you’re not sure. You need just 2 ingredients: real chocolate and heavy cream. I recommend Bakers or Ghirardelli brand baking semi-sweet chocolate bars, which is sold in the baking aisle near the chocolate chips.
***It took several test variations to learn that the consistency of the ganache (and how you swirl it) will make or break today’s cake recipe. If the ganache is too thin and warm, it will turn this into a thin chocolate banana cake batter. If it’s too thick, it will prevent the portions of cake batter surrounding it from baking so you’ll have this unpleasant and strange combination of baked and unbaked cake batter.***
How to avoid this: Let the ganache cool at room temperature for about 30 minutes until it’s about the consistency of gravy.
Perfecting the Banana Bundt Cake Batter
As the ganache cools and thickens, prep the cake batter. Banana cake was my starting point, but I add a little extra baking powder for some lift and slightly reduce the buttermilk. The original cake was strangely wet with the chocolate ganache, but after I reduced down the buttermilk, it cooked perfectly and had a lovely texture. If you’re looking for a plain banana Bundt cake, you can follow the recipe below and simply leave out the chocolate ganache swirl.
Layer in the cake batter and ganache, then generously swirl together.
Make Enough Ganache for the Topping
Everything is complete with a little accessorizing, so let’s finish this Bundt off with even more ganache. The recipe below instructs you to make all of the ganache at once, then save half for the topping after the cake bakes and cools. You’ll have to reheat it so it’s thin enough to drizzle. Feel free to halve the ganache, then garnish the cake with salted caramel or use the chocolate peanut butter topping from this chocolate chip loaf cake instead. (Readers have loved that topping!)
This is buttery moist banana Bundt cake swirled and topped with real chocolate ganache. Feel free to halve the ganache and only use it as the swirl. See step 1 below. For other garnish options, use salted caramel or the chocolate peanut butter topping from this chocolate chip loaf cake instead.
Ganache Swirl & Topping
- two 4-ounce quality semi-sweet chocolate bars (113g each), finely chopped
- 1 cup (8 ounces; 240ml) heavy cream or heavy whipping cream
- 3 large ripe bananas (about 1 and 1/2 cups mashed)
- 3 cups (375g) all-purpose flour (spoon & leveled)
- 1 and 1/2 teaspoons baking powder
- 1 teaspoon baking soda
- 1/2 teaspoon ground cinnamon
- 1/2 teaspoon salt
- 3/4 cup (170g) unsalted butter, softened to room temperature
- 1 cup (200g) granulated sugar
- 1/2 cup (100g) packed light or dark brown sugar
- 3 large eggs, at room temperature
- 2 teaspoons pure vanilla extract
- 1 and 1/3 cups (320ml) buttermilk, at room temperature*
- Preliminary Note: This cake is swirled and topped with chocolate ganache. If you aren’t topping the cake with ganache, halve the ganache recipe so you’re only making what you need for the swirl. (Use one 4 ounce chocolate bar and 1/2 cup (120ml) heavy cream.)
- Make the ganache: Place chopped chocolate in a medium heat-proof bowl. Heat the cream in a small saucepan over medium heat until it begins to gently simmer. (Do not let it come to a rapid boil– that’s too hot!) Pour over chocolate, then let it sit for 2-3 minutes to gently soften the chocolate. Very slowly stir until completely combined and chocolate has melted. The finer you chopped the chocolate, the quicker it will melt with the cream. You should have about 1 and 1/2 cups of ganache. Set half aside (3/4 cup or 180ml) at room temperature uncovered until it has thickened into a gravy-like consistency, about 30 minutes. Use this in step 7. Cover and refrigerate the rest of the ganache to use as the topping in step 10. Ganache topping can be refrigerated for up to 5 days before using.
- Preheat the oven to 350°F (177°C) and generously grease a 10-inch Bundt pan. To guarantee the Bundt cake releases seamlessly, I strongly recommend using a heavy coating of nonstick spray. Our favorite pans include this one and this one.
- Make the cake: Mash the bananas until there’s hardly any lumps. I usually just use my mixer for this! Set mashed bananas aside.
- Whisk the flour, baking powder, baking soda, cinnamon, and salt together. Set aside.
- Using a handheld or stand mixer fitted with a paddle attachment, beat the butter on high speed until smooth and creamy, about 1 minute. Add both sugars and beat on high speed for 2 minutes until creamed together. Scrape down the sides and up the bottom of the bowl with a rubber spatula as needed. Add the eggs and the vanilla. Beat on medium-high speed until combined, then beat in the mashed bananas. Mixture will be chunky and appear curdled– that’s ok. Scrape down the sides and up the bottom of the bowl as needed. With the mixer on low speed, add the dry ingredients in three additions alternating with the buttermilk and mixing each addition just until incorporated. Do not over-mix. The batter will be thick with some lumps. Makes about 6 cups of batter.
- You will use the slightly thickened ganache reserved for the swirl in this step. Pour about 1/3 of the cake batter (about 2 cups) evenly into prepared pan. Drizzle half of the ganache on top (about 6 Tablespoons). Swirl with a knife or toothpick. Evenly pour another 1/3 of the cake batter on top, followed by the rest of the ganache (about 6 Tablespoons), then the rest of the cake batter. Swirl everything together with a knife or toothpick. See photo above for a visual.
- Bake for 60-75 minutes or until a toothpick inserted into the cake comes out clean with just a couple lightly moist crumbs. This is a large, heavy cake so don’t be alarmed if it takes a little longer in your oven. If the cake is browning quickly in the oven, tent it with aluminum foil to help it bake more evenly.
- Once done, remove from the oven and allow to cool for 2 hours inside the pan. Then, invert the slightly cooled cake onto a wire rack or serving dish. Cool completely before topping, slicing, and serving.
- The ganache topping will be very thick by now. Warm it over low heat on the stove stirring constantly until thinned and drizzle-able consistency. Do not over-heat it. Or warm in 10 second increments in the microwave, stirring after each until thinned. Drizzle over cake, then slice and serve.
- Cover leftover cake tightly and store at room temperature for up to 2 days or in the refrigerator for up to 5 days. Cake tastes unbelievable warmed in the microwave for a few seconds and served with vanilla ice cream.
- Make Ahead Instructions: You can prepare the ganache used for the swirl and topping up to 5 days in advance. Make sure both are warmed/thinned out before using. The ganache used for the swirl should be a gravy-like consistency and the topping can be pretty thin. To warm/thin out, see step 10 above or step 5 in the chocolate ganache post. Cake with or without topping freezes well up to 3 months. Thaw overnight in the refrigerator, then bring to room temperature before serving.
- Chocolate: You can use high quality chocolate chips if needed (I prefer Ghirardelli semi-sweet chocolate chips), but I recommend using real chocolate baking bars. You can find them right next to the chocolate chips in the baking aisle. They are sold in 4 ounce bars. I like Bakers or Ghirardelli brands. You can use other varieties of chocolate too, such as milk chocolate (aka German Chocolate) or Dark Chocolate. Do not use white chocolate.
- Buttermilk: Buttermilk is required for this recipe. You can make your own DIY version of buttermilk if needed. Add 1 Tablespoon of white vinegar or lemon juice to a liquid measuring cup. Then add enough room temperature whole milk to the same measuring cup until it reaches 1 and 1/2 cups. (In a pinch, lower fat or nondairy milks work for this soured milk, but the cake won’t taste as moist or rich.) Stir it around and let sit for 5 minutes. The homemade “buttermilk” will be somewhat curdled and ready to use in the recipe.
Keywords: chocolate marble banana bundt cake