Chocolate Peanut Butter Fun Cake
The star of this chocolate peanut butter fun cake is the peanut butter buttercream frosting. It really is one of the most delicious cake toppers out there.
Ok, ok, I admit that “fun” in the title of the cake is a bit cheesy, but I’ll readily admit another point: this cake really is fun.
The entire dessert is less about the chocolate cake (just make sure you have a classically delicious, moist chocolate cake base) and more about the absolutely divine peanut butter buttercream frosting.
While we were eating this tasty treat, Brian and I must have said to each other at least four times, “This frosting is amazing” or “This cake is all about the frosting” or “This cake would be nothing without the frosting.” See how fun our conversation is at the dinner table? We are such fun people, it kills me.
The buttercream frosting is made using a method similar to a swiss meringue buttercream, which simply means that egg whites are cooked with sugar prior to whipping.
The silky texture and crazy-good creamy flavor of the frosting reminded me of this magical frosting, which I have already waxed poetic about in the past.
Softer and lighter than traditional buttercream frostings, this peanut butter buttercream was quite simply one of the most delicious concoctions I’ve ever topped a cake with. And it won’t be the last.
Garnished with roasted peanuts and chocolate shavings and you’ve got yourself the funnest cake of the century.
One Year Ago: Homemade Ciabatta Bread
Two Years Ago: Stir Fry Basil Chicken
Chocolate Peanut Butter Fun Cake
For the Cake:
- 1 ½ cups (213 g) all-purpose flour
- ¾ cup (159 g) granulated sugar
- ¼ cup (21 g) natural cocoa powder
- ¾ teaspoon baking soda
- ½ teaspoon salt
- ⅓ cup vegetable or canola oil
- 1 tablespoon distilled white vinegar
- 1 teaspoon vanilla extract
- 1 cup water
For the Peanut Butter Buttercream:
- ½ cup (106 g) sugar
- ¼ cup egg whites, from about 2 large eggs
- 1 ½ teaspoons vanilla extract
- ¼ cup (64 g) creamy peanut butter
- 6 tablespoons (85 g) butter, cut into 1/4-inch cubes
- ¼ cup (43 g) chopped semisweet or bittersweet chocolate
- ¼ cup chopped unsalted, dry-roasted peanuts, for garnish
- For the cake, adjust an oven rack to the middle position and heat the oven to 350 degrees F . Coat an 8-inch-square baking pan with nonstick cooking spray.
- Whisk the flour, sugar, cocoa, baking soda, and salt together in the baking pan. Make 1 large and 2 small craters in the dry ingredients. Add the oil to the large crater and vinegar and vanilla separately to the remaining small craters. Pour the water into the pan and mix until just a few streaks of flour remain. Use a rubber spatula to spread the batter evenly in the pan if it isn’t level after mixing. Immediately put the pan in the oven.
- Bake until a toothpick inserted in the center of the cake comes out with a few moist crumbs attached, about 23-25 minutes. Don’t overbake or the cake will be dry! Remove from the oven and let the cake cool completely in the pan set on a wire rack.
- For the buttercream, combine the sugar and egg whites in a medium metal or glass bowl set over a saucepan of simmering water. Whisk constantly until the sugar dissolves and the mixture is hot to the touch, 3–4 minutes.
- Remove the bowl from off the saucepan and using an electric mixer, beat on high speed until the mixture is cool and thick, 5–6 minutes. Beat in the vanilla, then the peanut butter. With the mixer running, add butter a few pieces at a time, beating to blend between additions. Season with a pinch of salt, if desired (I didn't add any additional salt to my frosting since I used salted butter).
- The frosting will be much softer and less set-up than a traditional buttercream made with butter and powdered sugar. If it seems overly runny, refrigerate the frosting for an hour or so to help it firm up – but keep in mind that this isn't a frosting to pipe with, it is meant to be soft and creamy. It has the finished texture of cream whipped to soft peaks.
- Run a thin knife around the cake pan to release the cake. Invert the cake onto a serving plate. Spread the peanut butter buttercream over top. Garnish with chopped chocolate and peanuts. The cake can be made and frosted up to 1 day ahead of time. Store airtight at room temperature.
Recipe Source: adapted from Bon Appetit
27 Comments on “Chocolate Peanut Butter Fun Cake”
Hi! Do you think the frosting could be made ahead, refrigerate for 36-48 hrs and then frost the cake before serving?
Hi Erin, I’m not entirely sure because I don’t know if the frosting will harden in the refrigerator, but it’s worth a try. Maybe take it out of the fridge an hour or so before needing to frost the cake.
I made this cake for my sister’s birthday. She requested chocolate/pb but wanted fluffy cake and fluffy frosting, so no brownie mousse concoctions. I’m glad I found this recipe! It fit the bill. The flavor of the cake was only so-so, but it was spongy. Word to the wise, read the recipe through! Mel has you mix it in the pan and I’d lined my pan with parchment, so it was a bit of a mess! The FROSTING though! I am not a frosting person. It’s usually sticky and heavy and thick and too sweet. This frosting was exceptional. It seemed a bit fussy reading through, but it honestly was pretty easy to make. The peanut butter flavor stood out and it was soft, fluffy, and not too sweet. It was almost like peanut butter marshmallow fluff. Make it for the frosting!!
Made this cake tonight for my sister’s birthday. The cake itself was just ok, but I’m not really a cake person to begin with. The frosting, though. Wow! It was unlike anything I’ve ever had. It was like peanut butter marshmallow fluff, but silky. It looked a bit complicated and intense, but ended up being pretty easy. I’m also not really a frosting person, but this was so much lighter, not too sweet and peanut-buttery. My sister, who is all about the fluffy cake and frosting. loved it!
Thoughts on doubling this and baking it in a 9×13? (I would frost it in the pan.)
Doubling would make a really thick cake but it would probably work…you could maybe 1 1/2 it for a 9X13? Just guessing since I haven’t tried it.
Just finished eating this cake all gone! I made two cakes, in 8-in round pans, for a stacked birthday cake. I put the (truly amazing and perfect and delicious) peanut butter frosting in the middle and it turned out fantastic!! (Frosted the whole cake with vanilla buttercream then covered with MM fondant.) The peanut butter frosting was a bit oozy, so I should have done a dam of frosting. Any cake pro would have already known that…and I just learned it! Anyway, 5-star rating from me!! 🙂
I made this frosting to put on top of your chocolate cupcakes perfected. A couple things I did different was use brown sugar instead of white sugar and added the peanut butter in after the butter had been incorporated. Holy Moly! Satin, buttery, heaven. I used a large round tip to pipe on top of cupcakes, drizzled with melted chocolate, then topped with chopped Reeses. They were a crowd pleaser!
This cake is delicious! I was trying to find a dairy free cake for my sister’s birthday and decided to give this a try. (I always know I can count on your recipes!) Since it’s Halloween time I had some Reese’s in the house and chopped some up as the topping. The cake was nice and fudgy and the frosting… WOW! WOW! WOW! My brother declared it the best cake he’s ever eaten and I would probably say the same! Thank you!
Amazing! First time in a while I’ve had dessert before dinner!
I have a chocolate cake with peanut butter frosting (a classic buttercream version) that we love, but I am going have to try this frosting method next time.
I am going to make this very soon. I might make it a bit healthier 🙂 and will let you know how it turns out. Thanks for commenting on my site and I hope you like the crispy bars :-). Beatiful family you have there!
I made the Bon Appetit version and I wasn’t impressed. I look forward to making the pb icing with your chocolate cake!
I fixed this cake for a family gathering. There was not a crumb left in the pan. I have never gotten so many complements on a dessert before. Thank you so much for all the hard work you do for this site. I have loved all of the recipies you have posted.
I can say, I’m stuck in your website. So many pretty pictures to seee *_*
Looks fun – and amazingly delicious! – to me!
ive never had peanut butter swiss meringue buttercream–ooh la la! and i like the name of this cake. 🙂
I came to your blog through another one. Your cake does look fantastic. It is probably the tastiest thing I have seen all day! Well done.
Hahaha Mel you crack me up. You ARE fun. And thats why I love getting your posts every day. Congrats on the new precious one!
Why would you need butter in this??? it is hard for me to picture this type frosting with butter. Curious!!!
My husband would LOVE this!!!!! Can’t wait to try it!
Ooo I saw this recipe in Bon Appetit and I’ve been DYING to try it! Your cake looks awesome! I can never resist pb and chocolate 🙂 This looks too good!
This looks amazing!!! Thanks for sharing 😀
Wow, looks fun for sure! 😉
I love how easy this is! Looks so yummy 🙂
You had me at chocolate & peanut butter- my favorite dessert combination! This looks crazy delicious, Mel. I know I will have fun eating it! 🙂