This is a single-layer banana cake made with mashed ripe bananas and sour cream, baked in a 9-inch round pan in about 45 minutes. The crumb is soft and stays moist for days, which makes it genuinely useful for baking ahead. If you have three bananas that are past their prime, this is the most straightforward thing you can do with them.
Why this recipe works
Two things carry this cake. First, the bananas must be truly overripe — skin deeply spotted or mostly black. At that stage the starches have converted to sugar and the fruit mashes smoothly into the batter, giving you both sweetness and moisture without any added liquid. Second, the sour cream does real structural work: its fat keeps the crumb tender while its acidity reacts with the baking soda, helping the cake rise evenly without a domed top. Those two elements together are why the texture holds up even on day three.
What can go wrong
- Bananas aren’t ripe enough: Yellow bananas with just a few spots will give you a bland, starchy cake. If yours aren’t ready, place unpeeled bananas on a baking sheet at 300°F for 15–20 minutes until the skins turn black. Let them cool before using.
- Butter and eggs are cold: Cold butter won’t cream properly and cold eggs can cause the batter to look curdled. Pull both from the fridge at least 30 minutes before you start.
- Overmixing after adding flour: Once the dry ingredients go in, stir only until you no longer see dry flour. Overworking the batter develops gluten and makes the cake tough and dense rather than tender.
- Pan not properly greased: A round cake pan has no forgiveness if the bottom sticks. Grease it, then cut a circle of parchment paper for the base — this takes 30 seconds and guarantees a clean release.
- Testing doneness too early: Ovens vary. Start checking at 40 minutes. The toothpick should come out clean or with a dry crumb — not wet batter. If the top is browning fast but the center is still wet, tent loosely with foil and continue baking.
Smart swaps
- Sour cream: Full-fat sour cream is the first choice. The recipe card notes Greek yogurt as a substitute — that works, but use full-fat Greek yogurt, not low-fat, or the cake will be slightly drier.
- Unsalted butter: If you only have salted butter, use it and leave out the ¼ teaspoon of salt in the recipe.
- Granulated sugar: You can swap up to half the granulated sugar for light brown sugar. It adds a mild caramel note that works well with banana. Skip the fancy raw sugars — they don’t cream the same way and can affect texture.
Storage and make-ahead
Once fully cooled, wrap the cake tightly in plastic wrap or store it in an airtight container. At room temperature it keeps well for up to 3 days — the texture is actually better on day two once the moisture has settled. Refrigerate it if your kitchen is warm, but bring it back to room temperature before serving since cold dulls the banana flavor. For longer storage, wrap individual slices in plastic and freeze for up to 2 months; thaw at room temperature for about an hour. You can also bake the cake a day ahead and frost or serve it the next day — it holds up without any loss of quality.
Decadent Banana Cake
Equipment
- 9-inch round cake pan
- Mixing Bowls
- Whisk
- Spatula
- Oven
- Cooling Rack
Ingredients
- 1 ½ cups all-purpose flour sifted
- 1 teaspoon baking soda
- ¼ teaspoon salt
- ½ cup unsalted butter softened
- 1 cup granulated sugar
- 2 large eggs room temperature
- 1 teaspoon vanilla extract
- 3 large ripe bananas mashed
- ½ cup sour cream
Instructions
- Preheat your oven to 350°F (175°C). Grease a 9-inch round cake pan and set aside.
- In a mixing bowl, whisk together the all-purpose flour, baking soda, and salt. Set aside.
- In another bowl, cream the softened butter and granulated sugar together until light and fluffy. This should take about 2-3 minutes.
- Add the eggs one at a time to the butter-sugar mixture, beating well after each addition. Stir in vanilla extract.
- Mix in the mashed bananas and sour cream until well combined.
- Gradually add the dry flour mixture to the wet ingredients, stirring gently until just combined. Be careful not to overmix.
- Pour the batter into the prepared cake pan, smoothing the top with a spatula.
- Bake in the preheated oven for 45 minutes or until a toothpick inserted into the center comes out clean.
- Allow the cake to cool in the pan for 10 minutes before transferring to a wire rack to cool completely.
Notes
Lori’s Tips:Â
- For enhanced flavor, add a pinch of cinnamon or nutmeg to the dry ingredients.
- Substitute sour cream with Greek yogurt for a tangier taste.
Nutrition
FAQ
Can I use a different pan size?
Yes, but you’ll need to adjust the bake time. An 8-inch round pan will give you a taller cake and may need an extra 5–8 minutes; a 9×5-inch loaf pan works too but plan for 55–65 minutes total. In either case, rely on the toothpick test, not the clock.
How do I know my butter and sugar are creamed enough?
The mixture should look pale — noticeably lighter in color than when you started — and feel fluffy rather than dense when you scrape the bowl. This takes about 2–3 minutes with a hand mixer on medium speed. Under-creaming means less air in the batter and a flatter cake.
Do I need to sift the flour?
The recipe calls for sifted flour, and it’s worth doing for this one. Banana batter is wet and dense, so sifting prevents flour clumps from hiding in the mix and ensures the baking soda distributes evenly. A fine-mesh strainer works just as well as a sifter.
Can I double the recipe to make a layer cake?
Yes — doubling the ingredients and baking in two 9-inch pans works well. Bake time stays roughly the same at 40–45 minutes since the batter depth per pan doesn’t change. Skip the garnish between layers if you’re using cream cheese frosting — the cake is rich enough that a simple spread is all you need, and it’s not worth the extra dish.
What to bake next
- Soft and Sweet Banana Bread Cookies
- Caramelized Banana Tart
- Nostalgic Malted Milk Chocolate Cake
- Autumn’s Spiced Pear and Almond Cake