This ultra-moist banana cake is so easy to make using a box of cake mix! I added ripe bananas and buttermilk to a dry mix to doctor it up into a mouthwatering sheet cake that tastes like a slice of banana bread. Finished with my simple cream cheese frosting, fresh banana slices, and crunchy walnuts, this easy cake is a textural delight!
Banana Sheet Cake with Cream Cheese Frosting
This super easy sheet cake is proof that a boxed mix can go a long way. I’ve made this simple banana cake for so many occasions over the years, and no one ever believes it’s not homemade! All it takes is a box of vanilla or yellow cake mix, some extra-ripe bananas to infuse it with moisture and flavor, plus a couple other basic ingredients.
I love using buttermilk to make the cake extra tender, but regular milk or water can be used in a pinch. And I always add cinnamon into the mix for some warmth. I usually make my own sweet-and-tangy cream cheese frosting to finish, but a store-bought frosting will taste just as good on top of this banana cake.
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Go Nuts!
I always top my banana cake with chopped walnuts after baking because it adds the perfect crunch. But you can also mix some directly into the batter if you want a true banana nut cake!
Banana Cake Recipe (Made with Cake Mix!)
Equipment
- 9×13 Baking Pan
- Hand Mixer
Ingredients
For the Cake:
- 15.25 ounces vanilla cake mix (1 box)*
- ½ cup vegetable oil **
- 2 large eggs room temperature
- 1 cup mashed bananas (from about 3-4 whole bananas)***
- ⅓ cup buttermilk room temperature
- ½ teaspoon ground cinnamon optional, but recommended
For the Frosting:
- 8 ounces cream cheese room temperature (1 brick)
- ¼ cup unsalted butter melted (½ stick)
- 1 teaspoon pure vanilla extract
- ⅛ teaspoon kosher salt
- 2½ cups powdered sugar
Optional Toppings:
- Chopped walnuts
- Banana slices
Instructions
Make the Cake:
- Preheat oven to 350°F. Grease a 9×13-inch baking pan and set aside.
- Add the oil, eggs, mashed bananas, and buttermilk to a bowl and whisk to combine.2 large eggs, 1 cup mashed bananas, ⅓ cup buttermilk, ½ cup vegetable oil
- Stir in the cake mix and cinnamon until well combined.15.25 ounces vanilla cake mix, ½ teaspoon ground cinnamon
- Transfer the batter to the prepared baking pan. Bake for 30-35 minutes, or until a toothpick inserted comes out clean.
- Let the cake cool completely before frosting.
Make the Frosting:
- Using a hand mixer, beat the cream cheese, butter, vanilla, and salt together.8 ounces cream cheese, ¼ cup unsalted butter, 1 teaspoon pure vanilla extract, ⅛ teaspoon kosher salt
- Beat in the powdered sugar, little by little, until incorporated.2½ cups powdered sugar
Assemble:
- Spread the frosting over the cake.
- Top with chopped walnuts and banana slices if desired.Chopped walnuts, Banana slices
Notes
- For best results, use room temperature dairy ingredients.
- Banana cake may turn out gummy if it is underbaked or if the batter is too wet. You want the batter to be thick but pourable, just like any normal cake batter. If your batter is too runny, you may need to add extra flour to thicken it up.
- Be sure to bake the cake until it passes the toothpick test to avoid an underbaked cake, which could collapse and turn gummy in the middle.
- If you notice black specks in your banana cake, there’s no need to be alarmed! They are banana seeds and are perfectly safe to eat!
- This cake can also be baked in two 9-inch round cake pans for 25-30 minutes, or as cupcakes for about 15 minutes.
- Nutritional information does not include optional toppings.
Baking with Bananas
- Use Over-ripe Bananas! Just like making banana bread, it’s important to use over-ripe bananas for this recipe. That means the peels should have plenty of brown spots all over. This ensures the bananas are sweet and soft, so they blend well into the cake mix and add lots of flavor.
- Not Ripe Enough? If your bananas aren’t quite ripe enough, poke them all over with a fork, place them on a plate, and microwave on high for 30 seconds at a time, until soft.
- Using Frozen Bananas? Make sure to thaw them and drain off any excess liquid before using. Thawing should make them soft enough to mix into the cake, although they may not be quite as sweet.
How to Make Banana Cake using Cake Mix Step-by-Step
Whisk the Wet: Preheat your oven to 350°F, grease a 9×13-inch baking pan, and set aside. Add ½ cup of vegetable oil, 2 large room-temperature eggs, 1 cup of mashed bananas, and ⅓ cup of room-temperature buttermilk to a bowl and whisk to combine.
Stir in the Dry: Next, stir 15.25 ounces (1 box) of vanilla or yellow cake mix and ½ teaspoon of cinnamon (if using) into the wet ingredients. Mix briefly until the wet and dry ingredients are combined. A couple of dry spots is fine.
Bake the Cake: Transfer the cake batter to the prepared quarter sheet pan. Bake banana cake for 30-35 minutes, or until a toothpick inserted comes out clean. Let the cake cool completely before frosting, or else the frosting will melt.
Make the Cream Cheese Frosting: Using a hand mixer, beat together 8 ounces (1 brick) of room-temperature cream cheese, ¼ cup of melted unsalted butter, 1 teaspoon of vanilla extract, and ⅛ teaspoon of kosher salt. Then beat in 2½ cups of powdered sugar, little by little, until incorporated and smooth. Or skip this step and use a store-bought frosting.
Frost the Cake: Spread the cream cheese frosting over the cooled banana cake, in an even layer.
Top and Serve: Top the cake with chopped walnuts and banana slices, if desired. I like to put one banana slice on each serving. If you’re making this cake ahead of time, I recommend waiting to add the bananas until just before serving, or else they will turn brown.
How to Store
Store leftover banana sheet cake in an airtight container in the refrigerator for up to 3 days, or in the freezer for up to 1 month. Let thaw overnight in the refrigerator before enjoying cold or at room temperature.
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