In this article
All week the bananas sat in the fruit bowl and nobody touched them. By Friday they had gone black and spotty, and anybody else would have thrown them out. My mother picked them up, squeezed them gently, and said, good, now they are ready. That was the signal for banana cake. Not banana bread, which she made too, but a real cake, baked in the big sheet pan and covered with cream cheese frosting so thick that my grandsons, years later, would eat it off the top first and leave the cake for afterwards.
She had a simple rule: the blacker the banana, the better the cake. By the time the skin goes dark, the starch inside the fruit has turned to sugar, and the banana mashes into something close to a syrup. That syrup is what makes the cake so moist, together with buttermilk, which keeps the crumb tender and reacts with the baking soda to lift the whole pan. The other secret is patience at the end: the frosting goes on only when the cake is completely cold, and the cake is kept covered so it stays soft for three or four days.
Why this banana cake works
- Very ripe bananas. Black bananas are sweeter and wetter than yellow ones, so the cake is moister and tastes far more of banana.
- Buttermilk. Its acidity tenderizes the crumb and gives the baking soda something to react with, so the cake rises light.
- Creamed butter and sugar. Beating them until pale traps air and gives a fine, soft cake rather than a dense loaf.
- Baked just to done. Taking the cake out as soon as a toothpick comes out with moist crumbs is the real secret to a cake that stays moist for days.
- Frosted cold, kept covered. A cold cake holds the frosting, and the frosting itself acts like a lid that keeps the moisture in.
Ingredients
Makes one 9x13 inch cake, about 16 squares. The measurements are in US cups with grams in brackets.
For the cake
- 3 very ripe bananas, black or heavily spotted (about 1 1/2 cups mashed, 340g)
- 2 3/4 cups all-purpose flour (345g)
- 1 1/2 teaspoons baking soda
- 1/2 teaspoon fine salt
- 1 teaspoon ground cinnamon (optional)
- 3/4 cup unsalted butter, softened (170g)
- 1 1/2 cups granulated sugar (300g)
- 3 large eggs, at room temperature
- 2 teaspoons vanilla extract
- 1 cup buttermilk, at room temperature (240ml)
For the cream cheese frosting
- 8 ounces cream cheese, softened (225g)
- 1/2 cup unsalted butter, softened (113g)
- 3 1/2 cups powdered sugar, sifted (420g)
- 2 teaspoons vanilla extract
- 1 pinch fine salt
Bananas that are only yellow will work, but the cake will be drier and less sweet. If yours are not ripe yet, bake them in their skins on a tray at 300 degrees for 15 to 20 minutes until the skins turn black, then cool and mash.
How to make banana cake
Make the cake
- Heat the oven to 350 degrees (175°C). Grease a 9x13 inch baking pan and line the bottom with parchment if you want to lift the cake out.
- Mash the bananas with a fork in a bowl until almost smooth, with only a few small lumps left.
- Whisk the flour, baking soda, salt and cinnamon together in another bowl.
- In a large bowl, beat the softened butter and sugar until pale and fluffy, about 3 minutes. Beat in the eggs one at a time, then the vanilla and the mashed bananas.
- Add the flour mixture in three parts, alternating with the buttermilk in two parts, mixing on low just until no flour shows.
- Spread the batter evenly in the pan and bake 30 to 35 minutes, until the top springs back and a toothpick in the center comes out with a few moist crumbs, not wet batter.
- Cool the cake completely in the pan on a rack, at least 1 hour. A warm cake will melt the frosting.
Frost it
- Beat the cream cheese and butter together until completely smooth, about 2 minutes.
- Add the powdered sugar a little at a time, then the vanilla and salt, and beat until thick and fluffy.
- Spread the frosting thickly over the cold cake with the back of a spoon or an offset spatula, making soft swirls. Cover and chill 30 minutes before cutting for clean squares.
Tips that make the difference
- Measure the mashed banana. Too much makes a heavy, gummy cake; about one and a half cups is right for this pan.
- Room temperature eggs and buttermilk blend smoothly into the butter. Cold ones make the batter look curdled.
- Do not overmix after the flour goes in. Stir just until it disappears so the cake stays tender.
- Start checking the cake at 28 minutes. Every oven is different, and a minute too long is what dries out a banana cake.
Variations
- Brown butter frosting. Brown the butter for the frosting, cool it until solid again, then beat it with the cream cheese for a nutty flavor.
- Walnut or pecan. Fold 1 cup of chopped toasted walnuts or pecans into the batter, or scatter them over the frosting.
- Layer cake. Bake the batter in two greased 9 inch round pans for 25 to 30 minutes and fill and frost with the same frosting.
- Chocolate chip. Fold 1 cup of mini chocolate chips into the batter for the grandsons.
Storage and make-ahead
Cover the pan tightly and keep the cake in the refrigerator because of the cream cheese frosting, up to 5 days. Let squares sit out 20 minutes before eating so the cake softens.
The unfrosted cake keeps, wrapped, at room temperature for 2 days, and it is even moister on the second day.
To freeze, wrap frosted squares individually in plastic and foil for up to 2 months, and thaw overnight in the refrigerator.
Frequently asked questions
How do I keep banana cake moist for days?
Use very ripe bananas, do not overbake, and keep the cake covered once it is frosted. The frosting seals the top, and a tight cover keeps the cut edges from drying out.
What is the difference between banana cake and banana bread?
Banana cake uses creamed butter and more sugar and eggs, so it is lighter and finer, like a true cake. Banana bread is denser and usually made with melted butter or oil and baked in a loaf pan.
Can I use frozen bananas?
Yes. Thaw them in a bowl, then pour in the liquid that comes out along with the fruit. It is pure banana flavor.
Can I make it without buttermilk?
Stir 1 tablespoon of lemon juice or white vinegar into 1 cup of milk and let it stand 5 minutes before using.
The next time the bananas go black on the counter, do what my mother did. Pick them up, smile, and turn the oven on.
Banana Cake with Cream Cheese Frosting (Moist for Days)
Old-fashioned banana sheet cake made with very ripe black bananas and buttermilk, baked in a 9x13 pan at 350 degrees and covered with a thick cream cheese frosting. Stays soft and moist for days.
Ingredients
- 3 very ripe bananas, black or heavily spotted
- 2 3/4 cups all-purpose flour
- 1 1/2 teaspoons baking soda
- 1/2 teaspoon fine salt
- 1 teaspoon ground cinnamon
- 3/4 cup unsalted butter, softened
- 1 1/2 cups granulated sugar
- 3 large eggs, at room temperature
- 2 teaspoons vanilla extract
- 1 cup buttermilk, at room temperature
- 8 ounces cream cheese, softened
- 1/2 cup unsalted butter, softened
- 3 1/2 cups powdered sugar, sifted
- 2 teaspoons vanilla extract
- 1 pinch fine salt
Instructions
- Heat the oven to 350 degrees (175°C). Grease a 9x13 inch baking pan and line the bottom with parchment if you want to lift the cake out.
- Mash the bananas with a fork in a bowl until almost smooth, with only a few small lumps left.
- Whisk the flour, baking soda, salt and cinnamon together in another bowl.
- In a large bowl, beat the softened butter and sugar until pale and fluffy, about 3 minutes. Beat in the eggs one at a time, then the vanilla and the mashed bananas.
- Add the flour mixture in three parts, alternating with the buttermilk in two parts, mixing on low just until no flour shows.
- Spread the batter evenly in the pan and bake 30 to 35 minutes, until the top springs back and a toothpick in the center comes out with a few moist crumbs, not wet batter.
- Cool the cake completely in the pan on a rack, at least 1 hour. A warm cake will melt the frosting.
- Beat the cream cheese and butter together until completely smooth, about 2 minutes.
- Add the powdered sugar a little at a time, then the vanilla and salt, and beat until thick and fluffy.
- Spread the frosting thickly over the cold cake with the back of a spoon or an offset spatula, making soft swirls. Cover and chill 30 minutes before cutting for clean squares.
