S'mores Cake with Marshmallow Meringue & Milk Chocolate Frosting

The sliced open s'mores cake, showing the layers of graham cracker cake, marshmallow fluff, and chocolate frosting.

5 from 1 vote

S'mores Cake with Marshmallow Meringue & Milk Chocolate Frosting

S'mores Cake has plush, moist layers of graham cracker flavored cake filled with homemade marshmallow fluff, and frosted in milk chocolate frosting. Pipe swirls of marshmallow fluff on top and toast it for the ultimate summer vibe. This is the ultimate way to enjoy a modern twist on a classic summer treat!

Prep Time1 30

Cook Time33

Course: Dessert

Cuisine: American

Keyword: Cake, S'mores, Summer

Servings: to 20 slices

Author: Stephanie Simmons

Ingredients

For the Graham Cracker Cake:

3 and 1/2 cups cake flour, spooned & leveled or weighed out 385 grams
3/4 tsp baking soda 4.5 grams
1 tbsp baking powder 14 grams
3/4 tsp salt 5 grams
1/4 tsp cinnamon
1/2 cup salted butter, softened at room temperature 113 grams
1/2 cup + 1 tbsp vegetable oil 131 grams
2 cups granulated sugar
2/3 cup brown sugar, packed light or dark both work!
3 large eggs, at room temperature
1 large egg white, at room temperature
1 tbsp vanilla extract
3/4 cup full fat sour cream, at room temperature 180 grams
1 and 1/2 cups milk, at room temperature 360 mL
1 cup graham cracker crumbs

For the Milk Chocolate Frosting

14 ounces milk chocolate You can use hershey's, milk chocolate chips, or any kind really! Just don't use candy coating.
1 and 1/2 cups salted butter, softened at room temperature 3 sticks, or 339 grams
5 and 3/4 cups powdered sugar Plus more to taste
2 cups cocoa powder
1-2 tbsp heavy cream or milk
1 tbsp vanilla extract
pinch of salt to taste
12 ounces full fat cream cheese, cold Use the block style, straight from the fridge

For the Marshmallow Meringue (Swiss Meringue)

4 large egg whites See note about separating eggs
1 cup granulated sugar
1/2 tsp cream of tartar
1/8 tsp salt
2 tsp vanilla extract or vanilla bean paste - I love seeing the flecks of vanilla!

For Assembly

3 whole graham crackers crushed into crumbs
1 full size hershey's bar

Instructions

Prep: Make sure all cold ingredients have come to room temperature. Preheat your oven to 350° F. Prepare three 9-inch cake pans. Use a paper towel to rub shortening all over the inside of each pan, coating them evenly and completely. Cut a round of parchment paper to fit inside each (tracing is the easiest way, or purchase parchment rounds). Place this on top of the greased pan bottom, then grease over the parchment paper as well. Add a handful of flour, and tap the pan around to evenly coat the entire inside with flour, tapping out the excess.
Make the Cake Batter: In a medium bowl, whisk together the dry ingredients – flour, baking powder, baking soda, cinnamon, and salt.
In a large mixing bowl, cream the softened butter for about 30 seconds, until creamy. Add the vegetable oil and beat together on medium high speed for 1 minute. Add the sugar and beat on high speed for 2 full minutes. The mixture will be fluffy. Scrape the sides of the bowl down throughout, to ensure everything is combined. Add the eggs, one at a time, beating on medium high speed between each addition, for 45 seconds. The mixture will be very fluffy. Add the sour cream and vanilla and mix on medium speed until just combined. Add half of the dry ingredients while the mixer is running on low speed. Add the milk when just a bit of the flour has disappeared into the batter, then add the remaining dry ingredients. Continue mixing on low, and stop when just a few streaks of flour remain. Turn off the mixer and dump in the graham cracker crumbs. Use a spatula to gently fold them in. Do not over mix - some lumps in the batter is perfectly ok.
Bake: Divide cake batter evenly between the prepared pans. (You can eyeball this or use a kitchen scale.) Bake the first two pans together, and then the 3rd pan on its own after the first two are done. This will ensure the most even bake. Bake the cakes for 23-26 minutes, rotating the pans halfway through (this helps them bake evenly). When done, a toothpick inserted into the center will pull out moist crumbs. Let cakes cool in the pans on cooling racks for 10 minutes. Then, invert onto cooling racks (peel off the parchment round) to cool completely.
Make the Frosting: While the cakes cool, make frosting. Melt the milk chocolate in a large mixing bowl, in 30-second intervals, stirring between each, then stirring vigorously after 2-3 intervals, using the residual heat in the bow to melt the remaining lumps. Allow to cool to room temperature. Beat the softened butter into the melted chocolate until well combined and smooth. Add the powdered sugar in two additions, mixing well between each, adding a splash of milk as needed to help it come together. Add all remaining ingredients except the cream cheese. Beat until combined, then mix in the cream cheese very last. Taste and add a bit more cocoa or powdered sugar as desired.
Meringue Prep: Make sure you read the note below on cleaning your utensils with vinegar before beginning. Get out everything you need before starting, including your cheesecake. Place your first cake layer on a serving plate, secured with a dollop of frosting. Set the serving plate on a cake turntable. Fill a piping bag fitted with a round tip (or with the end snipped off) with 1/2 cup of frosting.
Note: I have had better success making meringue in a stand mixer, but if you're confident with your hand mixer, you can use it as well. Try to avoid making this on a very humid day as that can wreak havoc on the meringue's stability.
Make the Marshmallow Meringue: Make this just before you are fully ready to assemble the cake - it can't just sit around waiting. Add an inch or so of water to a small/medium saucepan. Make sure your bowl doesn't sit in the water. Test it by setting the bowl on the pot, over the water, lifting off and seeing if the bottom is wet. If you have a stand mixer, you can use its metal bowl.
In your selected bowl, whisk together room temperature egg whites, granulated sugar, cream of tartar, and salt. Set the bowl over the pot of water. Turn the heat to low, then cook, whisking constantly until an instant thermometer holds steady at 175℉. (Mine was registering between 175℉ and 180℉ depending on where I stuck the thermometer without hitting the bottom of the bowl. Keep going until you don't see any reading below 175 ℉.) This will take about 8 minutes, but go by temp, not by time. Remove from the heat immediately, and add the vanilla.
Hand Mixer: Beat with a hand mixer on high speed for 4-5 minutes. We're looking for a thick mixture with stiff peaks.
Stand Mixer: Mix with the whisk attachment on high speed (I like to keep it between 8-9, not at 10) for 4-5 minutes. The mixture will grow up the sides of the bowl, and is ready when it seems to have stopped growing, and is balling up inside the whisk attachment (it will almost look a tad clumpy, as opposed to smooth & silky). When you lift the whisk attachment out and flip it so the bottom is pointing up, the meringue should stand stiffly up, with only the slightest bit of the tip top strand of meringue flipping over.
Assemble the Cake: Spread 1 and 1/2 cups of frosting over the first layer, spreading it evenly with an offset spatula. Pipe a border of frosting around the cake layer and fill with 1/4 of the marshmallow meringue. Toast it lightly with your torch, then sprinkle on a handful of graham cracker crumbs. Place the second cake layer on top and spread the excess frosting peeking out from between to begin your crumb coat around the first two layers. Chill in the fridge for 10-15 minutes to set things so the layers don't slide around.
Repeat with the second layer. Add the final layer upside down (for a flat top!) and give the cake a thin amount of frosting on top and on the sides. Use a cake scraper to smooth out and remove excess. This is your crumb coat, so don't fret if it isn't perfect. Pop the cake in the fridge for about 20 minutes to set the frosting. Then, apply the remaining frosting, using the cake scraper to smooth the top and sides of the cake. Let chill in the fridge for about 20 minutes or until frosting is set. Pipe the remaining marshmallow meringue on top of the cake, then torch it with your kitchen torch immediately. Add hershey's bar pieces on top of the cake for decoration, with a sprinkle of graham cracker crumbs.
Note: If you're worried you won't be able to work quickly enough frosting & assembling the cake, you can use store bought marshmallow fluff in between the layers, then swirl more on top. It can be toasted as well. Or, you can use fluff between the layers, and then a half batch of the homemade on top (store bought fluff isn't stable enough to pipe).
Serve & Store: Once the meringue has been piped on top, make sure the frosting isn't melty from being out, and slice & serve! The cake can also chill for 30-60 minutes if needed before serving. If your meringue stabilized to proper level (like mine in the photos) it will hold up for 4-6 hours before slicing & serving. Store leftover cake in an airtight container in the fridge, with plastic wrap pressed over the cut portion to keep it moist. Leftovers keep for 2-3 days.

Notes

Separating Eggs for Meringue: Eggs separate much more easily when cold, so separate your eggs about 30 minutes ahead of when you'll need them, and let the egg whites come to room temperature in a bowl on your counter.

Marshmallow Alternative: You can use store bought marshmallow fluff in place of homemade, however, it doesn't pipe like homemade does. So, you can swirl dollops of it into the frosting on top of the cake and lightly toast it. You can also toast mini or large marshmallows on a sheet pan using your torch (or do this under your oven's broiler - keep a close eye, it only needs 1-2 minutes!) to decorate the top of the cake with.

Work Quickly: Work quickly when frosting and assembling the cake, as the meringue can't hang around too long before being used. However, if you made it properly and it is stabilized, it will last through the time it takes to assemble the cake. If you haven't made many cakes and don't think you'll move quickly enough, there's a note about that in the recipe card above. You can swap fluff, or you can make half a batch of meringue, assemble and frost the cake, and refrigerate overnight. Just before serving the next day, make the remaining half batch of meringue and pipe it on top and toast it.

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