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Peanut Butter Sheet Cake

6 Reviews

This Peanut Butter Sheet Cake is for true peanut butter lovers. A layer of fluffy peanut butter cake is topped with a layer of lusciously creamy and easy peanut butter frosting.

2 slices of peanut butter sheet cake sitting atop one another

Easy Peanut Butter Sheet Cake

Hi there, Marie here from Sugar Salt Magic. When I need an excuse to eat peanut butter by the spoonful, sans judgement, this peanut butter sheet cake is the answer. It is a wonderful combination of not too sweet but super soft and moist cake filled with an unmistakable peanut butter flavour.

And that peanut butter frosting, sitting all swirly and soft on top, is more of that same PB flavor but in a creamy, melt in the mouth texture that just can’t be beat.

You’ve got to love a sheet cake. Perfect for family gatherings or dessert over a few days, they’re quick to make and just as delicious as a layer cake. This classic Chocolate Texas Sheet Cake is a family favourite, as is my Almond Lemon Poke Cake too.

This peanut butter cake is made in a 9×13-inch pan so you can get 24 serves out of it, but to be fair you’ll likely want to go back for a second piece, it’s that good.

This peanut butter sheet cake with its dreamy peanut butter frosting is truly a dream cake for peanut butter lovers. It’s loaded with PB flavour and easy to make — bonus points since it can be frozen so you can fulfill your PB cake desire whenever you need.

Close up of peanut butter frosting sprinkled with chocolate shavings

What’s in This Peanut Butter Cake? 

This peanut butter cake recipe uses mostly pantry staples. Here’s what’s needed for the peanut butter sheet cake itself: 

  • All-purpose flour
  • Baking powder
  • Salt
  • Brown sugar
  • Granulated sugar 
  • Creamy peanut butter 
  • Vegetable oil
  • Vanilla extract
  • Eggs
  • Whole milk

And for the peanut butter buttercream frosting, you’ll need: 

  • Unsalted butter
  • Creamy peanut butter
  • Powdered sugar
  • Salt
  • Vanilla extract

A montage of photos showing how to make peanut butter sheet cake

How to Make Peanut Butter Sheet Cake

This peanut butter cake recipe is a simple mix and go recipe. Here are the basic steps to making the peanut butter sheet cake itself: 

  1. Beat together creamy peanut butter, oil, sugar, and vanilla until it’s all mixed together well.
  2. Add eggs one at a time and make sure they are really well beaten in before moving on.
  3. In a separate bowl whisk together the flour, baking powder, and salt, then add 1 third to the wet mix and mix with a spatula until just combined.
  4. Alternate the milk and remaining dry ingredients, ½ of each at a time and stirring through with a spatula until just incorporated.
  5. At this point, you have what looks like a big bowl of peanut butter, yum! So pour it into your baking tin and level it out then bake for roughly 20 minutes. 

Tips for Making Peanut Butter Sheet Cake

  • You’ll get the best results from regular creamy peanut butter in this cake, as opposed to the natural PB types.
  • You’ll find two types of sugar in this cake – white and brown — and this combination is very important. All white sugar will leave your cake drier with a tighter crumb. All brown makes the cake far too dense but half of each gives it the perfect texture and flavour you need with slight caramel undertones.
  • ‘Whisking’ the dry ingredients separately takes just 30 seconds and I know it’s an extra bowl but doing this means your flour, salt and baking powder are not only evenly dispersed, but the whisk also helps to fluff the ingredients up which helps to add lightness to the cake.

2 images showing peanut butter frosting on a sheet cake

How to Peanut Butter Cake Frosting

The steps to making this easy peanut butter frosting could not be simpler:

  1. Beat together the peanut butter, butter and ¼ cup of the powdered sugar until smooth and creamy.
  2. Add the remaining powdered sugar ¼ cup at a time.
  3. Add the vanilla and salt, then beat for 2-3 minutes until it looks creamy and whipped.

Tips for Making Peanut Butter Buttercream Frosting

  • As with the cake, regular creamy peanut butter will give the best result.
  • Adding a little sugar right at the start helps the butter and peanut butter emulsify together.
  • Adding the rest of the sugar ¼ cup at a time is just to stop it puffing up all over the kitchen and you.
  • Brands of sugar, peanut butter and, for that matter butter, do vary in their moisture contents so you can thin or thicken the frosting with more or less powdered sugar to get it just the way you like.

slices of peanut butter sheet cake on a sheet of baking paper

How to Store Peanut Butter Sheet Cake

This cake keeps well for 3-4 days in an airtight container in the fridge. Let it come to room temperature before eating.

Can You Freeze Peanut Butter Cake?

You can definitely freeze this peanut butter cake, frosting and all. Sliced or unsliced is fine too. The very best way to freeze it is to place it into the freezer uncovered on the baking tray first, then:

  • Sliced – wrap the individual slices in plastic wrap before storing them in an airtight container for up to 2 months.
  • Unsliced / full cake – wrap the entire thing (cake pan included if you can spare it), in a layer of plastic wrap, followed by a layer of tin foil, then another 2 layers of plastic wrap. This will keep for up to 2 months.

Thaw the cake in the fridge overnight. Single slices are fine thawed at room temperature in about ½ an hour (depending on how warm or cool your home is).

a slice of peanut butter sheet cake on a white saucer

Can I Use Another Type of Frosting? 

Of course! Instead of making the peanut butter buttercream frosting, you could make a Caramel Frosting, Chocolate Frosting, or Nutella Frosting. 

Can I Substitute Another Nut Butter? 

I’m not sure! Different seed and nut butters have different consistencies, so be careful what you use in place of the peanut butter. 

More Peanut Butter Desserts: 

2 slices of peanut butter sheet cake sitting atop one another

Peanut Butter Sheet Cake

4.84 from 6 votes
Prep Time: 20 minutes
Cook Time: 20 minutes
Total Time: 40 minutes
Servings: 24
This Peanut Butter Sheet Cake is for true peanut butter lovers. A layer of fluffy peanut butter cake is topped with a layer of lusciously creamy and easy peanut butter frosting.

Ingredients

Peanut butter cake:

  • 2 cups (9 1/4 oz) all purpose flour
  • 2 teaspoons baking powder
  • 1/4 teaspoon salt
  • 1/2 cup brown sugar
  • 1/2 cup granulated sugar
  • 3/4 cup creamy peanut butter
  • 1/2 cup vegetable oil
  • 2 teaspoons vanilla extract
  • 2 large eggs
  • 3/4 cup whole milk

Peanut butter frosting:

  • 3/4 cup (1 1/2 sticks) unsalted butter , softened
  • 3/4 cup creamy peanut butter
  • 1 1/2 cups powdered sugar , sifted
  • 1/2 teaspoon salt
  • 1 teaspoon vanilla extract
  • Chocolate shavings

Instructions

Make the peanut butter sheet cake:

  • Preheat the oven to 350F. Grease and line a 9x13-inch baking tin with baking paper.
  • In a medium bowl, whisk together the flour, baking powder and salt.
  • In a large bowl, or the bowl of a stand mixer with paddle attachment, beat together both sugars, peanut butter, oil and vanilla until fully combined. Scrape down the sides.
  • Add the eggs, one at a time, beating well between each and scraping sides of bowl as necessary.
  • Add 1/3 of the flour mixture and fold through with spatula. Follow with half the milk and mix through gently, then repeat the process - flour, milk, flour.
  • Spread the batter into the prepared tin and bake for 18-20 minutes until a toothpick inserted comes out with just a crumb or two but not wet batter.

Make the peanut butter frosting:

  • Beat together the butter, peanut butter and 1/4 cup of powdered sugar until smooth and lightened.
  • With the mixer on low, add the sugar quarter of a cup at a time and continue to beat until fully combined.
  • Add the vanilla and salt, then beat on high for 2 minutes until fluffy and creamy.
  • Spread over the cooled cake then scatter with chocolate shavings.

Notes

It's always best to weigh flour using a kitchen scale to give the best results. If you use cups, make sure to fluff up the flour first, then spoon and level.
 
This cake will keep well for 3-4 days when covered.
Nutrition Facts
Peanut Butter Sheet Cake
Amount Per Serving (63 g)
Calories 270
* Percent Daily Values are based on a 2000 calorie diet.

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About the authors

carrian feik cheney oh sweet basil

Cade and Carrian have three children and love to spend time together whether it’s vacationing or snuggled up on the couch for a good movie.

And this family especially loves to eat.

They love everything from the keep you fit and healthy to the get out your sweat pants indulgent and everything in between.

But most of all, they love the memories made, shared and treasured and it’s all thanks to a meal shared together with loved ones.

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