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!
What you’ll love most about this chocolate marble banana Bundt cake is that unlike marble loaf cake, 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 or chocolate banana bread. 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.
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.
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.
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.