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Soft, sweet Banana Bars are topped with an almost fudge-like penuche frosting made with caramelized brown sugar and are the perfect way to use up the overripe brown bananas sitting on your counter! This recipe is essentially a frosted banana sheet cake, but great for cutting into bars and serving a crowd!

Banana desserts are so good and always a hit around our house! You might want to check out some of our most popular banana recipes like Homemade Banana Pudding or Paul’s favorite Old-Fashioned Banana Cream Pie.

a baking sheet with slices of soft banana sheet cake covered in penuche frosting

Banana Sheet Cake

If you go check, chances are you have some spotty bananas in your fruit basket just waiting to be used. If your family is anything like mine, some weeks you can’t keep the bananas long enough to make something with them and other weeks everybody is over bananas and you end up with a bunch of them getting mushy and overripe on the counter.

Of course, banana bread is always a good way to use them up. I have a coconut lime glazed version as well that is a fun and tropical change of pace! But let me introduce you to my other favorite way of using brown bananas: these addictive and irresistible banana bars with penuche frosting!

three banana bars with penuche frosting stacked on top of each other

I was at a church potluck a while back when I first spotted a plate of these unassuming looking bars. Amidst the sea of brownies and cookies, the caramel-looking frosting intrigued me. It was love at first bite. The frosting turned out to be a brown sugar penuche frosting, which is AMAZING. They seriously became the talk of the potluck with everybody standing around raving about how it was a total revelation to have what is essentially banana sheet cake with such a different frosting that none of us had tried before.

Turns out it was my friend Brian’s recipe and he was kind enough to share it with me so I could put it on the blog! Brian and his wife Jana are good friends (Jana actually helps me with blog stuff and if you are on my mailing list, she is the one who puts those together!) and have had us over for dinner numerous times. Brian’s go-to dessert is a sheet cake, but I definitely think of these banana bars as his signature dish.

sliced banana bars on a baking sheet

What is penuche frosting?

I’m so glad you asked. Penuche (puh-noo-chee) is basically fudge except made with caramelized brown sugar, butter, powdered sugar, and milk. It’s flavor reminds me a lot of pralines, if you have ever tried those!

Penuche frosting is basically the same thing except you pour it over the cake while both the cake and frosting are still hot. The timing gets a little tight and okay, it’s not the easiest frosting to work with, but man when you get it right it is incredible.

The ultra-soft, light, and fluffy banana cake is the perfect base for the penuche frosting which sets up on top for an amazing textural contrast. I know most banana bars and banana cakes are typically frosted with cream cheese frosting, which is delicious, but this penuche frosting really takes the cake (see what I did there?).

If you love this frosting as much as we do, you might also want to try these no-bake penuche cookies or add chopped pecans and turn it into penuche fudge!

a side image of banana sheet cake covered in penuche frosting

What You’ll Need

I love this recipe because we always have everything on hand to make them whenever my family goes off on bananas and I end up with a bunch that need to get used up!

  • Bananas: The recipe calls for 1 and 1/2 cups of mashed, ripe bananas. You can see how brown and ugly my bananas were in the photo below. It’s usually about 3 good size bananas, so if you don’t feel like mashing and measuring the bananas, you can skip that step and your banana bars will still turn out just fine.
  • Flour: Some regular all-purpose flour holds up well with the added moisture in this recipe.
  • Butter: You will need butter in both the cake part and the frosting part of the recipe. I almost always use salted butter in my baking and store extra butter in the freezer so I never run out!
  • Eggs: Two eggs help bind the cake together and give it some of its rise so it is light and fluffy.
  • Sugar: There is not doubt about it, this is a sweet treat! There is granulated sugar in the cake layer and the penuche frosting is made with brown sugar and powdered sugar.
  • Sour cream: I love this ingredient and it adds richness, moisture, and tang to the cake base. You can definitely sub Greek yogurt, and I haven’t tried but imagine this cake would also work with an equal amount of buttermilk or even regular milk if that’s all you have on hand.
  • Vanilla extract: This ingredient rounds out flavors in baked goods, making them have a more complex, interesting flavor. I love using my homemade vanilla extract!
  • Baking soda: This works as the leavening agent to lift the cake for a soft, light texture.
  • Milk: The milk is added to the melted butter and brown sugar to make the penuche frosting. Whole milk is my preference for any kind of cooking or baking, but lowfat will work just fine here as well.
ingredients for frosted banana bread bars

How to Make Banana Bars

  1. Cream butter, sugar, eggs, and vanilla: Start by beating the softened butter and sugar until they are light and fluffy. Then add in the eggs and vanilla and beat again. You can use a hand mixer or a stand mixer fitted with the paddle attachment.
  1. Add banana and sour cream: Add the mashed banana and sour cream, mixing it in and scraping down the sides of the bowl to combine and make sure there isn’t any of the butter and sugar mixture on the bottom that isn’t getting mixed in well.
  1. Add dry ingredients: Mix in the flour, baking soda, and salt, just until combined. Spread the batter into a greased half sheet pan. This is our most commonly used pan and it measures 18×13-inches with 1-inch sides. It’s perfect for sheet cakes and cookies!
  2. Bake: Sheet cakes bake pretty fast and this one is done within 20 minutes. It should be nice and golden brown on top and around the edges. You can test it with a toothpick inserted in the middle to see if it comes out clean, or by bouncing your finger lightly in the middle of the cake. If it leaves an impression, the cake might need to bake another minute or two longer. If it bounces right back, the cake is done.
  1. Make the penuche frosting: When the cake is about halfway done baking, it’s time to get going on the frosting so that it can finish right around the same time as the cake. Melt the butter in a medium saucepan over medium heat, then add the brown sugar, stirring frequently until the mixture comes to a boil. Stir in the milk, then remove from the heat and whisk in the powdered sugar. You need to work fast at this point because the frosting will set up pretty quickly. As soon as the powdered sugar is whisked in, pour the warm frosting over the warm cake and spread it out to cover the edges.
a banana sheet cake covered in penuche frosting
  1. Cut into bars: Let the frosting set for 30 minutes, then slice into bars with a small, sharp knife. You could make bigger squares and serve it like Texas sheet cake, but we like these best as bars that can be handheld, like brownies. Serve them warm, room temperature, or chilled from the fridge!
a baking sheet with sliced frosted banana bars

How to store banana bars

These bars stay fresh and delicious for days on the counter! Just keep them covered in a single layer in an airtight container. We usually just leave them in the pan they were baked in and cover it with plastic wrap so the edges don’t dry out. If you are tight on storage space, you could stack the bars in a smaller container. Just be sure to put a layer of wax paper or parchment paper in between them so they don’t stick to each other.

You can also freeze these banana bars for up to 2 months in the freezer. Thaw on the counter for a couple of hours before serving.

Serving suggestion

Of course these banana bars are yummy all on their own. You can keep things simple and just serve them with a glass of cold milk for an afternoon or evening treat!

But they are excellent with a scoop of ice cream. Vanilla goes with everything, but I also really like toasted almond ice cream or strawberry ice cream with these bars. And some sliced fresh fruit like peaches or strawberries can turn this from a simple dessert to something you might serve guests at the end of a nice meal.

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Banana Bars with Penuche Frosting
Yield: 24 servings

Banana Bars with Penuche Frosting

Soft, sweet Banana Bars are topped with an almost fudge-like penuche frosting made with caramelized brown sugar and are the perfect way to use up the overripe brown bananas sitting on your counter! This recipe is essentially a frosted banana sheet cake, but great for cutting into bars and serving a crowd!

Prep Time 15 minutes
Cook Time 20 minutes
Total Time 35 minutes

Ingredients

Cake

  • 1 and 1/2 cups sugar
  • 1/2 cup salted butter, softened
  • 2 eggs, room temperature
  • 2 teaspoons vanilla
  • 1 and 1/2 cups mashed ripe bananas (usually 3 bananas)
  • 1 cup sour cream, room temperature
  • 2 cups flour
  • 1 teaspoon baking soda
  • 1/2 teaspoon salt

Penuche Frosting

  • 1/2 cup salted butter
  • 1 cup brown sugar, packed
  • 1/4 cup hot milk
  • 3 and 1/2 cups sifted powdered sugar

Instructions

Cake

  1. Preheat the oven to 375 degrees F. Spray a half sheet pan with baking spray or line with parchment paper.
  2. In a large bowl, beat the sugar and butter together on medium-high speed for 2 to 3 minutes until creamy and light.
  3. Add eggs and vanilla, mixing to combine. Add the mashed bananas and sour cream, mixing and scraping down the sides and bottom of the bowl as needed.
  4. Add the flour, baking soda, and salt, mixing just until incorporated. Spread the batter into the prepared pan.
  5. Bake for 20 minutes until golden brown on top and a toothpick inserted in the center of the cake comes out clean.

Frosting

  1. Melt the butter in a medium saucepan set over medium heat. Add the brown sugar and bring to a boil, stirring frequently.
  2. Add the milk, then remove from the heat.
  3. Working quickly, whisk in the powdered sugar and pour over the still warm cake. Use a spatula to immediately spread the frosting around the top of the cake while it is still hot, then let it sit for 30 minutes to set up.

Notes

  • Adding nuts: These bars would be delicious with the addition of chopped walnuts or pecans, either in the cake itself or sprinkled on top of the penuche frosting before it has a chance to set.
  • Cream cheese frosting: If you would rather have a more traditional cream cheese frosting, this one is our favorite.
  • Storage: These will keep for about 5 days on the counter stored in an airtight container. Or you can freeze the bars for up to 2 months. Let thaw on the counter for a couple of hours before serving. The bars are delicious warm, cold, or room temperature.

Nutrition Information:

Yield:

24

Serving Size:

1

Amount Per Serving: Calories: 208Total Fat: 10gSaturated Fat: 6gTrans Fat: 0gUnsaturated Fat: 3gCholesterol: 42mgSodium: 170mgCarbohydrates: 28gFiber: 0gSugar: 19gProtein: 2g

All nutritional information is based on third party calculations and is only an estimate. Each recipe and nutritional value will vary depending on the brands you use, measuring methods and portion sizes per household.