You can never have too many banana cake recipes. This banana bars recipe is smothered with an easy peanut butter fudge frosting… AND feeds a crowd. Perfect for holiday entertaining or a pot luck.
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. At least they’re all good, if I may say so – especially this peanut butter, banana and chocolate chip cake.
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. Horror of horrors, 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.
Determined not to let that happen this week, I set myself the task of making a type of banana cake that isn’t already on the blog, and came up with these banana bars with peanut butter fudge frosting recipe.
This is great for this time of year, because it 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!).
I wanted to add a frosting. Surely you can’t have banana bars without a frosting, after all? But I didn’t want it to be a ‘hard work frosting’. Many frosting recipes I come across look and sound amazing, but lots of creaming and fluffing’s required to make them.
The peanut butter 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, personally, I couldn’t resist!
Banana sheet cake with peanut butter fudge frosting
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.
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).
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!
Begin checking the cake after 25 minutes as cooking time will vary a little depending on your oven.
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!