Peanut Butter S’mores Cake

 This Peanut Butter S’mores Cake features three layers of fudgey, rich chocolate cake, a toasted marshmallow filling and buttery graham cracker crumble, peanut butter frosting, and is topped with a chocolate ganache and marshmallow meringue… the perfect summer treat without lighting a campfire!

We went to Ruidoso, New Mexico with my family last week and had the BEST time!  Fireworks for the 4th, paddle boarding, horseback riding, coffee on the patio in the mornings, delicious food, and S’MORES!!!

It’s definitely s’mores season and if you’re a fan of toasty, gooey marshmallows and chocolate, you will DIE OVER THIS CAKE.

The chocolate cake itself is perfect in every way and I can’t wait to use it in more recipes.  I adapted it from I Am Baker (she is amazing!) and it is incredibly moist and fudgy, but still has a light cake crumb.  It has a deep, rich chocolate flavor, but is not overly sweet.  And don’t be turned off by the cup of coffee in it- there is not a coffee flavor after it bakes… It simply enhances the chocolate flavor!

The marshmallow filling is OUT OF THIS WORLD.  The recipe is from SweetapoKeyword: s’mores cake, s’mores dessert recipe lita’s Campfire Delight Cupcakes, and you actually toast marshmallows in the oven.  They are perfectly gooey and leave a little crispiness in the finished product. Straight from the campfire to your cake (minus all the smelly smoke in your hair and clothes)!  The marshmallow filling is topped with my favorite buttery graham cracker crumble (also used in my Key Lime Cake recipe).

To make this cake even more INCREDIBLE, I decided to frost it with the most delicious peanut butter buttercream.  This frosting may even give my perfect buttercream a run for its money.  It’s creamy yet fluffy, sweet yet salty, and melt-in-your-mouth amazing.

A chocolate ganache and a toasted marshmallow meringue completes this epic cake.  I had actually never made meringue before, and I wasn’t sure I was going to like it or even use it on my cake… but it was a.) DELICIOUS and b.) SO EASY!  Read my tips on meringue below before getting started.  Also, don’t sweat it if you don’t have a kitchen torch- the cake will still look beautiful!  If you have to have one though, this is the one I use.

Tips for Meringue:

• Make sure to completely clean and dry your whisk and metal (or glass) bowl.  If there is any trace of fat, the egg whites won’t reach their proper volume and you will have a whimpy meringue.
• Separate the egg whites and yolks when they are still cold, and then bring your whites to room temperature (at least 30 minutes).  If you separate them at room temperature, you are likely going to get yolk in your whites, and this can also cause your whites not to whip up properly.
• Make sure that your metal (or glass) bowl does not touch the simmering water in the pan.

One more note- this cake has quite a bit of steps and can feel daunting, so be sure to break it up!  I made the cake layers and graham cracker crumble one night, then the marshmallow filling, peanut butter frosting, and ganache the next morning.  I assembled it and then let it sit in the fridge for a couple hours, then came back and finished with the meringue.  It is totally doable!

If you make this cake, be sure to post a photo on Instagram and tag @asliceofsweet!

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Peanut Butter S’mores Cake

This Peanut Butter S’mores Cake features three layers of fudgey, rich chocolate cake, a toasted marshmallow filling and buttery graham cracker crumble, peanut butter frosting, and is topped with a chocolate ganache and marshmallow meringue… the perfect summer treat without lighting a campfire!

Course Dessert

Cuisine American

Keyword s'mores cake, s'mores dessert recipe

Servings 1 8-inch 3-layer cake

Ingredients

Chocolate Cake

• 1 3/4 cups all-purpose flour
• 2 cups sugar
• 3/4 cup unsweetened cocoa powder
• 2 teaspoons baking soda
• 1 teaspoon baking powder
• 1 teaspoon kosher salt
• 1 cup buttermilk, room temperature
• 1/2 cup vegetable oil
• 2 large eggs, room temperature
• 2 teaspoons vanilla extract
• 1 cup brewed coffee, hot

Toasted Marshmallow Filling

• 16 large marshmallows
• 1 cup powdered sugar
• 1 cup unsalted butter, room temperature
• ½ teaspoon vanilla extract
• 1 7 ounce jar Marshmallow Fluff

Graham Cracker Crumble

• 2 cups graham cracker crumbs
• 2 tablespoons sugar
• ½ cup 1 stick butter, melted and slightly cooled

Peanut Butter Buttercream

• 1.5 cups (3 sticks) unsalted butter, room temperature
• 1.5 cups peanut butter
• 1 teaspoon vanilla extract
• 6 cups powdered sugar
• 2-3 tablespoons heavy cream

Chocolate Ganache

• ½ cup semisweet chocolate chips
• ½ cup heavy cream

Marshmallow Meringue

• 5 large egg whites, room temperature
• 1.5 cups sugar

Instructions

Chocolate Cake:

1. Preheat oven to 350 degrees F. Lightly grease and flour 3 8-inch round cake pans lined with parchment paper (you can also use 2 9-inch but will want to bake longer).
2. Sift the flour, sugar, cocoa, baking soda, baking powder, and salt into the bowl and whisk until combined.
3. In the bowl of an electric mixer fitted with the whisk attachment, mix the buttermilk, oil, eggs, and vanilla.
4. With the mixer on low speed, slowly add the dry ingredients. With mixer still on low, add the coffee and stir just to combine. Pour the batter into the prepared pans and bake for 18-20 minutes, or until a cake tester or toothpick comes out mostly clean.
5. Cool in the pans for 30 minutes, then turn them out onto a cooling rack to cool completely.

Toasted Marshmallow Filling:

1. Place the marshmallows on a baking sheet lined with aluminum foil and sprayed with nonstick cooking spray. Place on the lowest rack of oven, and broil marshmallows until nice and brown on top (about 1 to 2 minutes- keeping an eye on them the entire time so they don’t burn). Remove pan from oven and gently turn the marshmallows over, and broil until the other side is golden brown.
2. Beat the butter and powdered sugar on low speed until blended together, about 1 minute. Add the vanilla extract and increase the speed to medium-high and beat for 3 minutes. Add the Marshmallow Fluff and toasted marshmallows, and mix on the lowest speed for 1 to 2 minutes, scraping the sides of the bowl as necessary.

Graham Cracker Crumble:

1. In a small bowl, combine the graham cracker crumbs, sugar, and melted butter and stir until well combined and crumbly. Spread mixture onto a cookie sheet lined with parchment paper. Bake at 350° F for about 5 minutes, then remove and set aside to cool.

Peanut Butter Buttercream:

1. With an electric mixer fitted with your paddle attachment, beat the butter on medium speed for about 2 minutes.
2. Add the peanut butter and beat until well combined (about 1 minute).
3. Add half of the powdered sugar and beat on low speed until combined. Add the remaining powdered sugar and beat until combined.
4. Add 1 tablespoon of heavy cream and beat on low speed for 30 seconds. Continue adding a tablespoon at a time until you reach your desired consistency. Beat for an additional 3-5 minutes on low speed.

Chocolate Ganache:

1. Heat the heavy cream in a microwave-safe bowl in the microwave until almost boiling, about 45 seconds. Add the chocolate chips and let sit for about 2 minutes. Slowly stir and well combined. Let ganache cool to room temperature before using (I place mine in the refrigerator for about 15 minutes to cool).

Marshmallow Meringue:

1. In a large, clean metal bowl, combine the egg whites and sugar (make sure the bowl is completely clean there is even a trace of fat in the bowl, the eggs won’t reach their proper volume).
2. Set the bowl over a saucepan with 2 inches of simmering water (make sure the water does not touch the metal bowl).
3. Heat the egg whites and sugar whisking constantly, until the sugar melts and there is no visible grains in the meringue (rub a little bit of the meringue between your fingers to make sure all the grains have melted).
4. Remove from the heat and beat using an electric mixer fitted with the whisk attachment on low speed for 5 minutes. Increase the speed to high and beat 5 minutes longer or until the meringue is stiff and shiny.

Assembly:

1. Place one cake layer upside down on a cake plate or stand and spread 1-2 cups of toasted marshmallow filling on the cake. Add a layer (about ½ - ¾ cup) of graham cracker crumbs on top. Repeat with second layer. Add third cake layer and frost a thin layer of peanut butter buttercream on the sides and top (crumb coat). I usually put it in the fridge or freezer at this point for 5-10 minutes and then add additional frosting to the top and sides. Add remaining graham cracker crumbs to the bottom of the cake.
2. Add half of the chocolate ganache to a drip bottle, and drip along the top edges of the cake. Add the remaining ganache on top of the cake and slowly smooth out with a knife or offset spatula, being careful not to let it run over the edges. Place cake in fridge for 30 minutes to an hour for the ganache to set.
3. Meanwhile, make the marshmallow meringue. Remove cake from fridge and using a knife or offset spatula, add marshmallow meringue to top of cake.
4. Torch with a kitchen torch, if desired.

Recipe Notes

Chocolate cake recipe adapted from I Am Baker, Marshmallow Filling from Sweetapolita, Marshmallow Meringue adapted from Rebecca Rather