S’moreo Cake with Toasted Marshmallow Oreo Filling

A summer favorite with a twist! My new S’moreo Cake uses Oreo cookies in place of graham crackers to create a chocolate lover’s dream cake. This S’moreo Cake is filled with chocolate cake layers, toasted marshmallow Oreo filling, chocolate ganache and chocolate cream cheese buttercream. It’s a must-make as you wrap up summer!

Chocolate cake with Oreos on top on a black cake stand.

What is a S’moreo?

First thing’s first: what is a S’moreo?

A S’moreo is a variation of a S’more! Instead of using graham crackers to sandwich chocolate and marshmallow, you’re using an Oreo.

S’moreo Cake

So what’s in my S’moreo Cake? This cake is layered with my favorite dark chocolate cake layers, toasted marshmallow Oreo filling, chocolate ganache, and chocolate cream cheese buttercream. On top, we slather the cake with more chocolate ganache, more buttercream, and mini marshmallows. Sounds pretty incredibly, right? It is! I know you chocolate lovers are going to be in heaven!

Close up of a chocolate drip on a chocolate cake.

The Best Chocolate Cake

It’s a big claim to call something “the best,” but I stand by this one more than any other claim I’ll ever make. This chocolate cake recipe truly is the best. Thanks to the rich, dark chocolate and loads of liquid in the recipe, this cake is moist, flavorful, and utterly decadent.

IMPORTANT: good quality cocoa powder makes a HUGE difference in the flavor and texture of your chocolate cakes. We want to use a cocoa powder that has high fat content. I always recommend Cacao Barry Extra Brute Cocoa Powder. It’s the best of the best.

NOTE: this batter is “runny,” so don’t let the consistency of the batter stress you out. It will bake beautifully and taste ultra moist.

Slice of chocolate cake on a plate.

Toasted Marshmallow Oreo Filling

This toasted marshmallow Oreo filling is nothing short of scrumptious! For this recipe, you’ll want to line a baking sheet with parchment paper. Then, make sure you spray the parchment paper with nonstick spray. As the marshmallows start to cook under your broiler, they will stick to the parchment if it’s not sprayed with nonstick spray.

Keep your eyes on the marshmallows as you’re toasting them. They’ll brown quickly. We want a little golden brown, but not burnt. Burnt marshmallows will get hard and will make it difficult to blend into the filling.

Feel free to use regular Oreos or double stuffed, just make sure you don’t scrape the filling out. Just chop the Oreos and throw them into the filling.

Girl eating chocolate cake.

Chocolate Cream Cheese Buttercream

To finish off this S’moreo Cake, we’re making my Chocolate Cream Cheese Buttercream from my Red Velvet Cookie Cake. This is easily one of my FAVORITE buttercreams and I know will make it on your top list too. I love the balance of the bittersweet chocolate with the tangy cream cheese.

Top side view of a chocolate cake with chocolate swirls and Oreos on top.
How to Make the Best Buttercream Frosting

For this silky, smooth and incredibly delicious buttercream frosting, you’ll want to make sure you follow the steps written in THIS blog post. I’d even bookmark that page to come back to as you’re mastering the art of buttercream.

The quick tips:

  • Use slightly cold butter
  • Sift the powdered sugar
  • Create a ganache with the heavy whipping cream and chocolate
  • Beat on a medium-high speed for several minutes
  • Stir by hand to push out the air pockets at the end.
Oreo cookies on a cake with a drip.

Other Chocolate Cakes You’ll Love

Cake on a cake stand.

S’moreo Cake

5 from 4 votes
Chocolate cake layers with toasted marshmallow Oreo filling, chocolate ganache and chocolate cream cheese buttercream.

Ingredients
 

FOR THE CAKE

  • 2 cups (240 g) all-purpose flour
  • 1 3/4 cups (350 g) granulated sugar
  • 3/4 cups (88.5 g) dark cocoa powder
  • 2 teaspoons (8 g) baking soda
  • 3/4 teaspoon (3 g) baking powder
  • 1 teaspoon (6 g) salt
  • 1 cup (240 g) buttermilk, at room temperature
  • 1 cup (236.6 g) hot water or coffee
  • 1/2 cup (109 g) vegetable oil
  • 3 large eggs, at room temperature
  • 1 teaspoon (4.2 g) pure vanilla extract

FOR THE MARSHMALLOW FILLING

  • 24 large white marshmallows
  • 1 cup (125 g) powdered sugar, measured and then sifted
  • 1 cup (226 g) unsalted butter ,at room temperature
  • 1/2 teaspoon (2.1 g) pure vanilla extract
  • 1 jar (200 g) marshmallow fluff
  • 8 Oreos, crushed into small to medium size pieces

FOR THE GANACHE

  • 1 cup (150 g) semi-sweet or dark chocolate chips
  • 1/2 cup (115.5 g) heavy whipping cream

FOR THE BUTTERCREAM

  • 1/4 cup (60 g) heavy whipping cream
  • 8 oz (150 g) good quality dark or semi sweet chocolate, chopped, melted and cooled slightly
  • 1 1/2 cups (339 g) unsalted butter, slightly cold
  • 5 cups (625 g) powdered sugar, measured and then sifted
  • 8 oz cream cheese
  • 1 teaspoon (4.2 g) pure vanilla extract
  • Pinch of salt
  • *This buttercream recipe makes enough to cover your cake. If you want to add additional piping you’ll want to make an extra ½ batch.

Instructions
 

FOR THE CAKE

  • Preheat the oven to 325 degrees F. Spray three 8-inch round cake pans with non-stick spray, line with parchment paper, and spray again. Set aside.
  • Combine the flour, sugar, cocoa, baking soda, baking powder, and salt into the bowl of an electric mixer fitted with a paddle attachment and mix on low speed until combined.
  • In another bowl, combine the buttermilk, water, oil, eggs, and vanilla.
  • With the mixer on low speed, slowly add the wet ingredients to the dry, scraping the bottom of the bowl with a rubber spatula.
  • Divide the batter between the three pans (about 16 ounces in each) and bake for 20 to 25 minutes, or until a toothpick inserted in the center of the cake comes out with a few moist crumbs on it.
  • Cool in the pans for 10 minutes, then turn them out onto a cooling rack and cool completely.
  • Wrap in plastic wrap and freeze until ready to use.

FOR THE MARSHMALLOW FILLING

  • Place the marshmallows on a cookie sheet lined with parchment paper and sprayed with nonstick cooking spray. Place on the middle rack of the oven, and broil the marshmallows until golden brown on top, about 30-60 seconds. Keep your eye on them!
  • Remove the pan from the oven and gently turn the marshmallows over and broil them again until they are golden brown on the other side.
  • In the bowl of a stand mixer fitted with the paddle attachment, combine the butter and powdered sugar and beat on low until blended. Add the vanilla and mix on medium speed for about three minutes
  • With the mixer on low speed, add the marshmallow cream and (cooled) toasted marshmallows, and mix for about one minute.
  • Fold in the crushed Oreos

FOR THE GANACHE

  • In a microwave safe bowl, pour the cream over the chocolate chips and heat for about 45-60 seconds. Stir, and if needed, heat for another 30 seconds to melt the chocolate chips completely. Let cool to room temperature before using.

FOR THE BUTTERCREAM

  • Combine the heavy cream and the chocolate chips in a microwave safe bowl. Heat the mixture for a minute and stir to melt the chocolate chips to create a ganache. Set aside.
  • In the bowl of a stand mixer fitted with the paddle attachment, beat the butter and cream cheese for about 2 minutes on medium-high speed.
  • Gradually add the chocolate ganache, scraping down the sides and bottom of the bowl as you go. Stir the mixture until smooth and silky.
  • With the mixer on low, gradually add the powdered sugar, followed by the vanilla and salt. Turn the mixer to medium-high speed and beat the frosting for about 5 minutes.
  • Before frosting the cake, use a wooden spoon to mix the frosting by hand to push out air bubbles and create a smooth and silky texture.

ASSEMBLY

  • Level each chocolate cake layer, if needed, and then place the first cake layer, top side up, on a cake board.
  • Spread about half of the marshmallow Oreo filling over the cake layer and then drizzle with the chocolate ganache.
  • Repeat with second layer.
  • Place the final cake layer, top side side down, on top and cover with a thin layer of the buttercream. Freeze the cake for 10 to 15 minutes to set the crumb coat.
  • Finish frosting the cake with the remaining buttercream.
  • For the drip, you’ll want to heat up an additional ¼ cup heavy cream, add it to the ganache and stir until the mixture is thinner, as seen above.
Cuisine Cake
Course Dessert
Keyword Chocolate Cake, chocolate cream cheese buttercream, Intermediate, marshmallow, S’moreo, S’moreo Cake, Smores Cake, summer cake

Courtney Rich

I’m a self-taught baker, obsessed with cake.

I long ago ditched box mixes in pursuit of melt-in-your-mouth, to-die-for flavor combinations, fillings and textures. I believe cake must be decadent, life-changing and worthy of celebration! And I believe anyone should be able to bake that kind of cake – and I’m here to teach you just that!

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Comments

  1. With cream cheese in the frosting, should the cake be stored in the fridge before serving, or can it sit out on the counter prior to serving?

  2. 5 stars
    Yet another favorite of your cakes. Absolutely delicious!!! I made it for a staff meeting, which required it to sit out beforehand, so I subbed your amazing chocolate buttercream for the cream cheese based frosting called for in the recipe (I was worried the cream cheese frosting wouldn’t fare well. Would it have worked??). I brought a slice home and even my husband, who is not a “sweets guy,” told me to make it again.

  3. 5 stars
    The filling in this cake was amazing! The oreos didn’t get soggy and gave a nice crunchy texture to the cake. The cake was incredibly moist and had a good depth of chocolate flavor. A new favorite!