This Peanut Butter Sheet Cake takes less than an hour to make from start to finish. It’s topped with a fudgy, candied peanut butter icing that’s out-of-this-world amazing! Recipe includes a how-to video.
A Peanut Butter Lover’s Dream Cake
Sure, layer cakes are impressive, but there’s something to be said about classic, from-scratch sheet cakes. Their ease (no leveling, layering, crumb coating), flavor (just as good!), and nostalgic, homey feel is simply unparalleled in the cake world. Today’s tender peanut butter sheet cake is no different; it’s simple, flavorful, and is decorated and served right in its baking dish. It’s a classic!
This cake has a balanced peanut butter flavor that’s prominent without being too overwhelming. My favorite part is the frosting though…it’s like a candied peanut butter fudge topping! It’s super rich (so we use just the right amount) and pairs beautifully with the texture of the cake.
I think you’re really going to love this one, so let’s dive right in!
What You Need
Here are the key ingredients in this peanut butter sheet cake:
- Peanut butter. Do NOT use “natural” peanut butter that separates! Unfortunately, in many peanut butter recipes (like my buckeyes, peanut butter balls, and the frosting on my peanut butter chocolate cake) readers have reported oily failures when they tried to use natural peanut butter, so best bet is to avoid it here. I prefer to use creamy peanut butter, but crunchy could be used instead.
- Butter. I highly recommend using unsalted butter in this recipe (and most of my others!). I have a post comparing salted vs. unsalted butter that you can check out if you’d like an in-depth explanation, but essentially, unsalted butter allows for better precision. This is especially important when using a salted ingredient like peanut butter
- Buttermilk. If you don’t have buttermilk, you can always use my easy buttermilk substitute, but the real stuff will give you the best flavor and moisture.
- Brown sugar. Light brown sugar adds some depth to the cake that really complements the peanut butter flavor well, like in my peanut butter cookies.
- Baking soda. Make sure to use baking soda and not baking powder–they are not the same thing! If you want to learn more about the differences between the two, read my post on baking powder vs. baking soda.
SAM’S TIP: When making your frosting, you’ll want to stir CONSTANTLY once the butter melts. When the mixture comes to a boil, remove it immediately to prevent any burning.
Remember, this is just an overview of the ingredients I used and why. For the full recipe please scroll down to the bottom of the post!
How to Make It
- Whisk together the dry ingredients and sugars in a large bowl and set aside.
- Bring oil, butter, and water to a boil over medium heat.
- Remove the pan from the heat and stir in your peanut butter until it’s melted and smooth.
- Pour your peanut butter mixture into your dry ingredients and mix until combined. Let cool 5-10 minutes.
- Combine buttermilk, eggs, and vanilla, then stir this into your prepared batter until just combined.
- Pour batter into a greased pan and bake for 30-32 minutes.
- Measure and sift your sugar, then set it aside.
- Cook buttermilk, butter, peanut butter, and salt over medium-low heat until the butter melts, then increase heat to medium and whisk constantly.
- Once the mixture boils, remove it from the heat and whisk in the powdered sugar and vanilla.
- Pour the icing over the warm cake and use an offset spatula to smooth.
SAM’S TIP: Once your frosting is fully prepared, you need to work quickly to get it on the cake. The frosting will solidify somewhat, and you want that to happen on the cake–not in the bowl!
Frequently Asked Questions
Nope! Not unless you want it refrigerated, anyway. Simply store at room temperature covered or in an airtight container and enjoy within three days.
Definitely! When I first published this recipe, I used my peanut butter frosting (with some chocolate added to half the batter for a swirl), so that’s always an option. My Texas sheet cake frosting, my chocolate fudge frosting, or just about any other frosting would work well, too.
Yes! You’ll want to wrap it well and store in an airtight container for up to three months.
Baking, decorating, and serving all in the same pan–the beauty of a sheet cake!
Enjoy!
Let’s bake together! I’ll be walking you through all the steps in my written recipe and video below! If you try this recipe, be sure to tag me on Instagram, and you can also find me on YouTube and Facebook
Peanut Butter Sheet Cake
Ingredients
Sheet Cake
- 2 cups (250 g) all-purpose flour
- 1 cup (200 g) granulated sugar
- ¾ cups (150 g) light brown sugar firmly packed
- ¾ teaspoon baking soda
- ¾ teaspoon salt
- 1 cup (237 ml) water
- ¾ cup (177 g) unsalted butter cut into pieces
- ¼ cup (60 g) avocado, canola or vegetable oil
- ½ cup (145 g) creamy peanut butter
- ½ cup (118 ml) buttermilk
- 2 large eggs room temperature preferred
- 1 ½ teaspoons vanilla extract
Fudgy Peanut Butter Frosting
- 4 cups (500 g) powdered sugar
- ½ cup (118 ml) buttermilk
- 10 Tablespoons (150 g) unsalted butter cut into pieces
- ⅔ cup (165 g) creamy peanut butter
- ¼ heaping teaspoon salt
- 1 teaspoon vanilla extract
Recommended Equipment
Instructions
- Preheat oven to 350F (175C) and lightly grease a 13×9 baking pan. Set aside.
- In a large bowl, whisk together flour, sugars, baking soda, and salt.2 cups (250 g) all-purpose flour, 1 cup (200 g) granulated sugar, ¾ cups (150 g) light brown sugar, ¾ teaspoon baking soda, ¾ teaspoon salt
- In a medium-sized saucepan, combine water, butter, and oil. Heat over medium heat, stirring occasionally until butter is melted and bring to a boil.1 cup (237 ml) water, ¾ cup (177 g) unsalted butter, ¼ cup (60 g) avocado, canola or vegetable oil
- Once boiling, remove from heat and add peanut butter. Stir until peanut butter is dissolved and mixture is smooth. Add to bowl with dry ingredients and stir until combined. Set aside to cool for 5-10 minutes.½ cup (145 g) creamy peanut butter
- Meanwhile, in a separate bowl, whisk together buttermilk, eggs, and vanilla extract.½ cup (118 ml) buttermilk, 2 large eggs, 1 ½ teaspoons vanilla extract
- Gradually stir buttermilk mixture into batter, stirring until just combined.
- Pour batter evenly into prepared pan and transfer to center rack of 350F (175C) preheated oven and bake for 30-32 minutes or until a toothpick inserted in the center comes out clean or with moist crumbs. Prepare frosting.
Fudgy Peanut Butter Frosting
- Measure out sugar and set aside (if you’re worried about lumps in your icing, sift the sugar after measuring).4 cups (500 g) powdered sugar
- Combine buttermilk, butter, peanut butter, and salt in a medium-sized saucepan. Cook over medium-low heat until butter is melted. Increase heat to medium and bring to a boil while stirring constantly. Once boiling, remove from heat.½ cup (118 ml) buttermilk, 10 Tablespoons (150 g) unsalted butter, ⅔ cup (165 g) creamy peanut butter, ¼ heaping teaspoon salt
- Immediately add powdered sugar and vanilla extract.1 teaspoon vanilla extract
- Whisk until smooth and immediately pour evenly over cake (in the pan, I do not remove my cake from the pan).
Notes
Jelly Roll Pan
To bake in a jellyroll pan (15×10″ pan) bake on 350F for 18-22 minutes.Peanut Butter
I recommend against using a “natural” variety of peanut butter (the kind where the oil separates out) as this could affect the texture of the cake.Creamy or crunchy peanut butter will work here, I prefer creamy for smoother results, but if you opt for crunchy you’ll just have small peanut pieces in your cake and icing.
Storing
Cover the pan with foil or plastic wrap and store at room temperature for up to three days.Nutrition
Nutritional information is based on third-party calculations and should be considered an estimate only. Actual nutritional content will vary based upon brands used, measuring methods, cooking method, portion sizes, and more.
Carolynn
Awesome. Very moist and easy to make. Instructions were easy to follow and well written. Thankyou for sharing. Well definitely make again.
Sam Merritt
I’m so glad you enjoyed it so much, Carolynn! 🙂
Tina
This is thee best cake I’ve ever made. I’ve made it several times and gave the recipe out as well. Thank you so much for sharing it!
Emily @ Sugar Spun Run
Thanks so much, Tina! We are so happy it’s such a hit 🥰
DmDiva
This is a fa favorite at my Wednesday night church supper! The best peanut butter cake ever!
Sam
I’m so glad you enjoyed it so much! 🙂
Stella
So good and peanut butter-y!
Sam
I’m so glad you enjoyed it so much, Stella! 🙂
Melanie Teeters
Thanks so much for including the measurements for each step after the instructions. I’ve lost my place so many times having to scroll back and forth to get the right amount.
Sam
I’m so glad it was helpful, Melanie! 🙂
Grace
Hi Sam!
I’d love to make this recipe for a layered birthday cake, ideally 3 layers. Do you think the recipe would need to be doubled (I would make the recipe twice) for a 3 layer, 8 inch round cake? Any advice on how to adjust the baking time? It always makes me nervous to modify a recipe from a rectangular pan to a round pan. Thank you so much!
Emily @ Sugar Spun Run
Hi Grace! Doubling would probably make too much batter, so multiplying the recipe by 1.5 would probably be best. We honestly haven’t tried baking this cake in smaller pans though, so we can’t say what the bake time would be. You should be relieved to know that several readers in our Facebook group have successfully made the cake as a 2-layer cake rather than a sheet cake 😀
Aubrey
I made the icing, but it turned out way thinner than yours. I’m not sure what I did wrong. Do you have any ideas? Thanks 🙂
Sam
Hi Aubrey! Did you let it set up while cooling? Did you make any adjustments to the frosting? It is a more runny frosting but sets up as it cools. 🙂
Luanda
hey Sam. happy New Year. Sam can I bake this cake on a 9 in round pan, will it come out the same
Emily @ Sugar Spun Run
Hi Luanda! We haven’t tried it, but we think it could work. As written, it will make enough for at least two pans though.
Eric
Nice step by step instructions great tasting
Stephanie
Best peanut butter cake and icing, ever!!
Emily @ Sugar Spun Run
We’re so happy you enjoyed it, Stephanie! 🥰
Alexandra
Amazing for hosting Thanksgiving.