Banana slice with peanut butter fudge icing


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You can never have too many banana cake recipes. This banana bars recipe is smothered with an easy peanut butter fudge icing… AND feeds a crowd. Perfect for holiday entertaining or a pot luck.

A close up of banana cake with peanut butter frosting and peanut butter cups on top with a big piece cut out.

It’s getting to the point where it’s slightly embarrassing how many banana and/or peanut butter cake recipes I have on this blog:

I told you…

But I keep posting them because a certain person in our house (who isn’t me) won’t eat bananas as soon as they start to look remotely ripe. He even sometimes puts them in the bin before I can snatch them up and either make something with them or pop them in the freezer for later.

So I do ‘need’ plenty of ripe banana recipes!

What’s so great about this banana slice recipe?

  • The recipe makes quite a lot of cake, serving around 20. It would be a perfect pot luck contender for that family gathering or holiday party with friends.
  • It’s lovely and moist, like banana cakes should be, but still quite cake-y rather than banana bread-y, if that makes sense. Which is how I imagined it to be (result!).
  • The peanut butter fudge icing is to die for – and very easy to make.
  • A piece of this banana snack cake is only around 250 calories. Not exactly healthy cake, but not too bad either!
Someone slicing into Banana sheet cake with peanut butter fudge frosting with a big knife.

How to make it

This banana slice is really easy to make. You make them like a classic banana cake: cream together butter and sugar, add mashed banana and yoghurt, stir in dry ingredients.

Bake, let cool, then add the quick and easy frosting and decorations!

How to make the icing

The frosting recipe I went for has 5 ingredients in it – just peanut butter, butter, milk, vanilla, and powdered sugar. But what makes it so easy is the fact that you simply melt the first 4 ingredients together in a saucepan, then stir in the powdered sugar.

No whipping or piping required.

What you end up with is a fudge-y, buttery, peanut butter-y deliciousness to spread thickly over your sheet cake.

Sprinkle over some chopped up peanut butter cups, peanut butter M&Ms, or Reese’s pieces for a bit of extra decadence if you like. You can skip this step if you like, but it isn’t recommended!

Collage of 2 images showing banana sheet cake in a baking dish from above and ingredients for the frosting in a saucepan.
Someone eating A piece of banana cake with peanut butter frosting with a fork on a white plate with bananas in the background.

More easy snack cake recipes



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closeup of a blue baking dish of banana slice with peanut butter icing with a big slice taken out.
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Banana slice with peanut butter fudge icing

A banana sheet cake with an easy peanut butter fudge icing. Great for feeding a crowd!
Prep: 20 minutes
Cook: 30 minutes
Total: 50 minutes
Servings: 20


For the sheet cake

  • 1 1/2 sticks of butter
  • 1 cup sugar
  • 1/2 cup brown sugar
  • 3 eggs
  • 1 cup mashed ripe banana, 2-3 bananas, depending on size
  • 1 1/2 teaspoons vanilla essence
  • 1 1/2 tablespoons buttermilk or sour milk, (see note below)
  • 2 1/2 cups plain flour
  • 1 teaspoon baking powder
  • 1/2 teaspoon baking soda
  • 1/2 teaspoon salt
  • 1/2 teaspoon ground cinnamon

For the peanut butter fudge topping

  • 3/4 stick of butter
  • 4 tablespoons milk
  • 1/3 cup peanut butter
  • 2 teaspoons vanilla essence
  • 2 1/2 cups powdered / icing sugar, powdered / icing sugar
  • 6 peanut butter cups, chopped into pieces (optional)


  • Lightly butter a 9 x 13 inch cake pan / baking dish and preheat the oven to 175C / 350F (170C / 340F fan oven).
  • In a food mixer or food processor (or in a bowl with a hand-held electric whisk), soften the butter (about a minute), then add the sugars and cream together until light and fluffy (about 2 minutes).
  • With the motor / whisk running, add the eggs one by one until combined, then whisk in the mashed banana, vanilla, and milk.
  • In a separate bowl, sift the flour together with the baking powder, baking soda, salt, and cinnamon.
  • Slowly add the flour mixture to the wet ingredients (pour wet mixture into a bowl if you’ve used a food processor), mixing until just combined.
  • Pour the batter into the cake pan / baking dish and bake for 30 minutes or until a skewer inserted into the centre of the cake comes out pretty clean. Leave to cool in the pan.
  • Meanwhile, make the frosting. Combine the butter, milk, peanut butter and vanilla in a saucepan and heat and stir until melted together.
  • Slowly add the powdered / icing sugar until you have a smooth and thick frosting. Pour over the cake and spread evenly.
  • Sprinkle over the chopped peanut butter cups (if using). Pop the whole pan in the fridge or freezer for a short while to set the frosting a bit, then slice and serve.


Don’t have any buttermilk?

If you don’t have any buttermilk and don’t want to buy any just for this recipe, simply add about ¾ tablespoon vinegar or lemon juice to ordinary milk and let stand for 5 minutes (I always do it this way, as buttermilk isn’t a standard ingredient here in the UK).

Mixing the batter

Don’t overmix after you add the dry ingredients to the wet. Just mix the flour in until just combined. A bit lumpy is fine!

Cooking time

Begin checking the cake after 25 minutes as cooking time will vary a little depending on your oven.

Decorating the cake

Feel free to use Reese’s Pieces or Peanut Butter M&Ms instead of Peanut Butter Cups for decoration – or just skip this final step altogether!


Calories: 251kcal, Carbohydrates: 48g, Protein: 4g, Fat: 4g, Saturated Fat: 1g, Cholesterol: 25mg, Sodium: 138mg, Potassium: 142mg, Fiber: 1g, Sugar: 34g, Vitamin A: 50IU, Vitamin C: 1mg, Calcium: 30mg, Iron: 1.1mg
Like this recipe? Rate and comment below!

About Helen Schofield

Don't expect to find anything fussy or complicated here. Just QUICK, EASY & (mostly!) HEALTHY recipes from the Mediterranean and beyond. ENJOY!

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    1. Hi Dee! This is one of my older recipes so I’m not sure what I was thinking when I wrote ‘a stick of butter’!!! It’s a common American measurement, but it just means 113 grams (or 4 ounces). Good luck with the recipe! The bars are delicious!

  1. Oh… my… gawd! Oh Helen, this looks amazing! I love how banana makes anything you bake so wonderfully moist, and the combo of chocolate and peanut butter – win, win, win!

    1. Thanks for your vote of approval, Kathleen! You can’t really go wrong with this combo of ingredients, can you?

  2. Miam! Tes photos me donnent envie de plonger dedans l’ordinateur! C’est juste irrésistible! Il faut pas s’excuser pour avoir tant des recettes avec la banane et le peanut butter, c’est tellement bon! x

  3. Moist and loving that frosting. I am super glad you have loads of banana and peanut butter cakes on your blog. I have my sights on your banana and pistachio bread! Mmmmmm. Sharing, of course.

  4. I have been looking for a good banana sheet cake recipe for a while. And I am sure the peanut butter topping here is just an added bonus for my husband!!

    1. Hi Zainab! So nice to hear from you! I hope you get around to trying this some time. 🙂

  5. I love banana cake. I love peanut butter and banana. However, I have never thought to put them together! Genius! I have to make this!

  6. Banana and peanut butter are one of the best flavor combinations so there’s nothing wrong with how many desserts you can come up with, them more the better. I live with a peanut butter cup fanatic so I’ll have to make this soon.

  7. I have a special obsessions with banana sheet cakes! Cannot wait to try your PB fudge frosting, Helen. Looks too good for words! <3 Pinned!