Layers of moist banana cake dotted with chocolate chips and frosted with the creamiest chocolate buttercream – this banana chocolate chip cake is pure heaven. It’s flavorful from ripe bananas without being overly sweet. You can also make it in a 9×13 inch pan if you prefer. 
This banana chocolate chip cake tastes like an elevated slice of warm banana bread perfect for celebration. The cake is tender and extremely moist with a mellow banana flavor complemented by hints of brown sugar, vanilla and cinnamon. Mini chocolate chips are folded through the batter and the whole cake is finished with a rich, creamy chocolate buttercream. It’s intentionally not too sweet, which keeps the banana flavor front and center.
Baking Tips, Tricks and Things to Note
- The recipe combines butter and oil: butter for flavor, oil to keep the cake moist longer. Make sure the butter is softened to room temperature before starting.
- Eggs and buttermilk should be at room temperature so ingredients incorporate smoothly without overmixing.
- Use exactly 1 1/4 cups mashed bananas. That will require about 3–4 very ripe bananas depending on size. Measure after mashing rather than relying on a banana count.
- Choose brown, spotty bananas for the best moisture and sweet, mellow flavor. Yellow or green bananas won’t yield the same results.
- Avoid overmixing the batter; overmixing makes the cake tough. Expect some lumps from the mashed banana—this is normal.
- Mini chocolate chips are recommended. Regular chips are heavier and can sink, and they make slicing less tidy.
- Don’t add too many chocolate chips. Excess chips can affect the cake’s structure and make it crumbly when sliced.
Assembling the Cake
Always assemble the cake when the layers are completely cool. Pro tip: bake the layers the night before, let them cool, then wrap and store at room temperature. Make the frosting and assemble the day you plan to serve.
If the cake tops are domed, level them with a cake leveler or serrated knife so layers sit evenly.
- Place the first cake layer top side down on your serving plate (the leveled side facing up) and spread about 1/4–1/3 of the frosting over it.
- Top with the second layer, also placed top side down.
- Apply a thin layer of frosting to the sides to seal crumbs (the crumb coat). This prevents crumbs from showing through the final frosting layer.
- Chill the crumb-coated cake for about 20 minutes to firm the coating.
- Finish by frosting the sides and top with swirls of creamy chocolate buttercream.
Pan Sizes
This recipe makes a generous amount of batter. You can bake it in:
- two 9-inch round cake pans — bake 35–40 minutes at 350°F (180°C; 170°C fan)
- three 8-inch round pans — bake 25–30 minutes at 350°F (180°C; 170°C fan)
- one 9×13 inch (23×33 cm) pan — bake 50–55 minutes at 350°F (180°C; 170°C fan)
About the frosting: The frosting recipe is enough for a double-layer or a triple-layer cake (with slightly thinner coverage on a triple layer). For a double-layer you may have a little extra frosting for piping or decorations. If you bake the cake in a 9×13 pan, halve the frosting ingredients.
Equipment
- Two 9-inch cake pans (see pan alternatives above)
Ingredients
Banana Chocolate Chip Cake
- 2 3/4 cups all-purpose flour
- 1 teaspoon baking powder
- 1 teaspoon baking soda
- 1 teaspoon cinnamon
- 1/2 cup unsalted butter, softened
- 1/4 cup vegetable oil (canola works)
- 1 cup granulated sugar
- 1/2 cup packed brown sugar (light or dark)
- 2 teaspoons vanilla extract
- 3 large eggs, room temperature
- 1 1/4 cups mashed bananas (measure after mashing; about 3–4 brown bananas)
- 1 1/2 cups buttermilk (or see notes for a substitution)
- 1 cup mini chocolate chips
Chocolate Frosting
- 1 1/4 cups unsalted butter, softened
- 3/4 cup cocoa powder
- 3–4 cups powdered sugar, sifted if lumpy
- 1 teaspoon vanilla extract
- 1/2 teaspoon salt
- 3–4 tablespoons whipping cream or milk, as needed
Instructions
Banana Chocolate Chip Cake
- Preheat oven to 350°F (180°C or 170°C fan).
- Line the bottoms of two 9-inch pans with parchment rounds and lightly grease the sides.
- Whisk together flour, baking powder, baking soda, cinnamon and salt; set aside.
- In a large bowl, beat butter with granulated and brown sugar until smooth and lump-free (about 1 minute). Beat in the oil.
- Add vanilla, then beat in eggs one at a time, pausing to scrape the bowl as needed.
- Turn off the mixer and stir in the mashed bananas by hand.
- On low speed, add about one-third of the dry ingredients, then scrape the bowl and add about half the buttermilk. Continue alternating remaining dry ingredients and buttermilk, finishing with the dry ingredients. Some banana lumps are expected.
- Fold in the mini chocolate chips gently with a spatula or wooden spoon.
- Divide the batter evenly between prepared pans and bake on the middle rack for 35–40 minutes, or until a toothpick inserted comes out with a few moist crumbs. (A completely clean toothpick can sometimes be misleading with this cake.)
- Cool the layers in the pans for about 20 minutes, then invert onto a wire rack to cool completely.
Frosting
- Sift cocoa and powdered sugar if lumpy.
- Beat the butter until smooth.
- With the mixer on low, add 2 cups powdered sugar and beat into the butter.
- Add cocoa, vanilla and salt and beat on low to combine.
- Add remaining powdered sugar 1/2 cup at a time, alternating with 1 tablespoon cream or milk until you reach the desired sweetness and consistency. Adjust liquid and sugar to get a spreadable frosting.
Assembling & Frosting the Cake
- Ensure cake layers are completely cooled.
- Level the rounded tops with a cake leveler or serrated knife.
- Place the first layer top side down on your serving plate and spread 1/4–1/3 of the frosting on top.
- Set the second layer on top, top side down, and apply a thin crumb coat to the sides. Chill 20 minutes if needed.
- Finish frosting the sides and top with swirls of frosting.
Notes
- Pan options:
- Two 9-inch round pans: bake 35–40 minutes.
- Three 8-inch pans: bake 25–30 minutes.
- One 9×13 pan: bake 50–55 minutes. If using a 9×13 pan, halve the frosting ingredients (see the quantities below): 1/2 cup + 2 tbsp butter, 1/4 cup + 2 tbsp cocoa, 1 1/2–2 cups powdered sugar, 1/2 tsp vanilla, 1/4 tsp salt, 1–2 tbsp cream.
- Bananas: Use brown, spotty bananas for flavor and moisture.
- Buttermilk substitute: Add 1 1/2 tablespoons freshly squeezed lemon juice to a measuring cup and fill to 1 1/2 cups with 1% or 2% milk. Stir and let sit briefly before using.
- Make-ahead: Bake layers the day before, cool completely, wrap tightly and store at room temperature. Frosting and assembly the next day. Layers can also be frozen up to 2 months, wrapped well; thaw overnight in the fridge.
- Storage: Store covered at room temperature for up to 3 days or in the fridge for up to 4 days.
- Nutrition: Nutrition values are estimates for one of 12 slices and assume all frosting is used. Slice counts and values may vary.
Nutrition (estimate per slice)
Calories: 782 kcal; Carbohydrates: 107 g; Protein: 8 g; Fat: 38 g; Saturated Fat: 21 g; Sugar: 78 g; Sodium: 259 mg; Fiber: 4 g.
Banana Chocolate Chip Cake
Prep: 1 hr • Cook: 35 mins • Cooling: 3 hrs • Total: 4 hrs 35 mins • Servings: 12 slices