S'Mores Sheet Cake

s'mores cake on parchment with large marshmallows, graham crackers, and crumbs

A sweet cinnamon spiced cake, topped with a rich dark chocolate ganache, and finished with a homemade marshmallow fluff! This S'more Sheet Cake is the ultimate summertime baking treat.

Course: Cakes and Cupcakes

Cuisine: American

Prep Time: 25

Cook Time: 40

Additional Time: 2

Total Time: 3 5

Servings: slices

Calories: 313kcal

Ingredients

Cinnamon Cake

3 cups all purpose flour
2 cups granulated sugar
1 Tablespoon baking powder
1 teaspoon salt
1 Tablespoon ground cinnamon
3 large eggs
1 cup whole milk
1 teaspoon vanilla extract
¾ cup unsalted butter melted

Chocolate Ganache

1 cup bittersweet chocolate chips
1 cup heavy cream

Marshmallow Topping

3¾ teaspoons unflavored gelatin
½ cup water divided
¾ cup granulated sugar
⅛ teaspoon salt
½ cup corn syrup
1½ teaspoons vanilla extract

Instructions

Cinnamon Cake

Heat oven to 350℉/177℃.
Spray an 8-inch x 12-inch pan with baking spray. Set aside.
In a large bowl, whisk together flour, sugar, baking powder, salt, and cinnamon. Set aside.
Beat eggs, milk, and vanilla together.
Add wet ingredients to dry ingredients.
Whisk to combine.
Stir in melted butter.
Pour into prepared pan and bake for about 25 minutes, until cake tests done.

Ganache

Combine chocolate and cream in a microwave safe bowl.
Heat in 15 second increments, stirring after each, until chocolate is melted and mixture is smooth.
Cover ganache with a piece of plastic wrap touching the chocolate to prevent skimming.
Place in refrigerator for 20-30 minutes, or until it thickens.

Marshmallow Topping

Combine gelatin and ¼ cup water in the bowl of a stand mixer.
In a saucepan, combine remaining ¼ cup water, sugar, salt, and corn syrup.
Cook over medium heat until sugar dissolves, stirring continually.
Once sugar has dissolved, stop stirring.
Brush the sides of the pan down with a pastry brush dipped in warm water.
Allow to cook, without stirring, to 240℉/116℃ on a candy thermometer.
Remove from heat.
With mixer running at low speed, slowly pour in syrup.
Continue beating for 5 - 10 minutes, until thickened but still soft.

Assembly

Spread chocolate ganache on top of cooled cake.
Let sit for about 5 minutes, until firm.
Spread marshmallow topping on cake.
Using a kitchen torch, toast the marshmallow topping.

Notes

Substitutions:

Store-bought marshmallow fluff works if you’re short on time, but homemade is fluffier and easier to spread.
Swap dark chocolate for milk or semi-sweet, depending on your preference.

Tips For Success:

You can make the cake ahead of time, but it’s best to make the ganache and marshmallow topping fresh for assembly.
If the marshmallow fluff becomes difficult to cut, lightly heat it with a kitchen torch before serving to soften it again.
Make sure not to over mix the cake batter!
You can make the ganache over a bain-marie (double boiler) or by heating the milk, pouring it over the chocolate, and letting it stand for a few minutes before stirring.
The ganache needs to still be spreadable when you remove it from the refrigerator.

How To Store:

Store any leftovers in an airtight container. The cake can be stored in the fridge for up to 3 days.
You can also store the cake base separately in the freezer and assemble it the day of serving.

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