Peanut Butter Sheet Cake With Dark Chocolate Frosting

Amy Manes
by Amy Manes
16 slices
1 hr 20 min

If your favorite candy is a Reese’s peanut butter cup, then this peanut butter sheet cake is just the thing you need! It’s loaded with creamy peanut butter and topped with a dark chocolate cream cheese frosting that just takes it over the top. I love this cake because it pleases a variety of people, so it’s perfect for sharing with others! This peanut butter sheet cake would make a yummy birthday cake or treat for any special occasion, such as an anniversary! You’re going to want to keep this recipe on hand all year long to use for a variety of occasions!

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Well, friends, it’s been a while but I’m back in the blog world and ready to tackle 2022! I’ve got lots of yummy recipes planned for the year, so you’re going to want to stick around to see what I’m baking! If you’re not subscribed already and want my recipes sent straight to your email, then sign up here so that you don’t miss any! You’ll be the first to know of any Buckets of Yum updates and fun things happening!

Alright, now onto the peanut butter sheet cake! This cake is just… yes. It’s everything you could ever want in life! Made of moist peanut butter cake and topped with a creamy dark chocolate frosting – it is just irresistible! If you love peanut butter cups, then this is YOUR dessert! Read on for how to make this yummy peanut butter sheet cake!

Ingredients for the Best Peanut Butter Sheet Cake

I really like this peanut butter sheet cake because it’s a crowd-pleaser and almost anyone will love it! It’s a great recipe to have on hand for birthday parties, gatherings, or just a weekday treat! I guarantee you’ll repurpose this one all year.

The ingredients for this peanut butter sheet cake are really quite simple, and you likely already have them on hand!

Here’s what you’ll need for the peanut butter sheet cake:

  • Butter
  • Oil – I used canola oil, but any neutral-flavored oil will do!
  • Creamy Peanut Butter – You MUST use creamy peanut butter for this! You will want your cake to be smooth and fluffy. Any creamy PB will do! I used Jif All Natural Peanut Butter for mine.
  • Brown Sugar
  • Granulated Sugar
  • Baking Powder
  • Baking Soda
  • Salt
  • Eggs
  • All-Purpose Flour
  • Buttermilk – If you don’t have buttermilk on hand, substitute with 1 cup minus 1 tbsp. of milk, and then add in 1 tbsps. of lemon juice or white vinegar! Let it curdle for 5 minutes or so and you have buttermilk!
  • Sprinkles

And then for the dark chocolate cream cheese frosting:

  • Cream Cheese
  • Unsalted Butter
  • Unsweetened Cocoa Powder – If you’ve been around here long enough, you that Rodelle Cocoa Powder is my absolute fave! It’s so rich in chocolate flavor and is one of the best on the market.

High Altitude Adjustments

For reference, I live at 5,800 feet. These adjustments would likely give you the result that you are looking for if you live within a few hundred feet of where I am at. But high altitude baking can be a lot of trial and error! This, however, should then give you a starting point to go off of to experiment with your own ingredients at whatever elevation you live at! I would also recommend checking out this guide here.

High Altitude Adjustments for Cake

  • Flour – increase by 2 tbsp. Additional flour helps to strengthen the structure of the baked good so that it will rise correctly. At 3,500 feet, add 1 more tbsp. of flour per recipe. For each additional 1,500 feet, add one more tablespoon.
  • Baking Powder – decrease to 1/2 tsp. You can see this table on King Arthur’s website for how to adjust leavening agents for higher elevations (scroll down a ways to the “Leavening” section on their site). For my elevation, I typically cut all leavening agents in half. This allows for the right chemical reactions to happen between the other ingredients for the perfect rise. If there is too much leavening within the batter, not all of it gets used up (not all of it reacts with the other ingredients), so you are left over with a soapy bitter-tasting baked good due to the excess baking soda or baking powder in the batter.
  • Baking Soda – decrease to 1/4 tsp. I found that 1/4 tsp. worked well in this recipe.
  • Granulated Sugar – decrease by 1/2 tbsp. This should hold true at most high elevations. Always decrease your sugars by 1 tbsp. per cup.
  • Brown Sugar – decrease by 2 tsp.
  • Eggs – use 4 instead of 3. This will keep the baked good from drying out at a higher baking temperature and evaporation rate. If I am baking a cake or cupcakes, I like to add one more egg to increase the liquids in the recipe. This should hold true at most higher elevations, but experiment with it, of course!
  • Increase oven temperature to 360° F. Since rising and evaporation proceed more quickly at higher elevations, you will want to use a higher baking temperature to set the structure of the baked goods so that they don’t sink in the middle and dry out on the edges. I recommend starting with increasing the baking temperature stated in the recipe by 15° F and go up from there in small increments (all the way up to 25° F increase if needed).
  • Decrease baking time by 5 or more minutes. This is because you will be baking at a higher temperature. You don’t want your cake to burn! I usually decrease by 5-8 minutes per 30 minutes of baking time and adjust from there. Keep a close eye on your dessert in the oven while you are experimenting with time and baking temps.

I hope that you enjoy this gooey peanut butter sheet cake with dark chocolate frosting! It will be a staple recipe to have around for birthdays, anniversaries, and plenty of other celebrations. Enjoy!

As always, be sure to tag me in your photos on Instagram if you make my recipe! I love to see what you are baking.

Peanut Butter Sheet Cake With Dark Chocolate Frosting
Recipe details
  • 16  slices
  • Prep time: 45 Minutes Cook time: 35 Minutes Total time: 1 hr 20 min
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For the Peanut Butter Cake
  • 3/4 cup unsalted butter
  • 1/4 cup canola oil (or other neutral-flavored oil)
  • 2/3 cup creamy peanut butter
  • 3/4 cup brown sugar (packed)
  • 1/2 cup granulated sugar
  • 1 tsp baking powder
  • 3/4 tsp baking soda
  • 1/2 tsp salt
  • 3 large eggs (room temperature)
  • 2 cups all-purpose flour
  • 1 cup buttermilk
For the Dark Chocolate Frosting
  • 8 oz cream cheese (room temperature)
  • 1/4 cup unsalted butter (room temperature)
  • 1/2 cup unsweetened cocoa powder
  • 3 cups powdered sugar
For the Peanut Butter Cake
Preheat oven to 350°F. Line a 9×13 inch cake pan with parchment paper so that the edges are hanging over the long sides and then grease with butter or cooking spray (I like Pam for Baking).
In a small saucepan over medium heat, stir the butter until it is melted. Remove the pan from the heat and whisk in peanut butter and oil until incorporated. Transfer the peanut butter mixture to a glass bowl or liquid measuring cup to cool.
In the bowl of a stand mixer fitted with the paddle attachment, combine the sugars, baking powder, baking soda, salt, and eggs. Mix on low speed until moistened and then increase speed to high. Beat until thick, fluffy, and pale (about 7 minutes).
Reduce the mixer speed to low and slowly pour in the peanut butter mixture. Mix until evenly incorporated. Add the flour and mix until just combined. Some streaks of flour will remain. Slowly beat in the buttermilk until just combined, do not overmix.
Transfer batter to the prepared pan and evenly spread (batter will be thick and heavy).
Bake until a toothpick inserted in the center comes out clean, about 30 – 35 minutes. Cool in pan before frosting.
For the Dark Chocolate Frosting
In the bowl of a stand mixer fitted with the paddle attachment, beat the cream cheese and butter on medium speed until smooth (about 2 minutes). Scrape the bowl as needed.
In a separate bowl, whisk together the cocoa and powdered sugar. With the mixer on low speed, slowly add the cocoa and powdered sugar mixture and mix until well blended. Increase speed to high and beat until fluffy and creamy.
Frost the cake using a knife or offset spatula. Top with sprinkles if desired and enjoy!
  • Cake will last for 5 days stored in an airtight container in the refrigerator. Bring to room temperature before serving.
  • High Altitude Directions:
  • -Flour – increase by 2 tbsp
  • -Baking Powder – decrease to 1/2 tsp
  • -Baking Soda – decrease to 1/4 tsp
  • -Granulated Sugar – decrease by 1/2 tbsp
  • -Brown Sugar – decrease by 2 tsp
  • -Eggs – use 4 instead of 3.
  • -Increase oven temperature to 360° F
  • -Decrease baking time by 5 or more minutes
Amy Manes
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