This Chocolate Iced S’mores Cake and Toasted Marshmallows takes everything you love about a campfire s’more and turns it into a big, sharable dessert. You get a buttery graham cracker base, soft and moist chocolate cake, glossy chocolate icing, and a thick blanket of toasted marshmallows on top.

Every slice has the perfect s’mores trifecta: graham, chocolate, and marshmallow, with gooey, slightly smoky marshmallows that brown just like they do over a fire. It’s perfect for parties, potlucks, birthdays, or any time you want a nostalgic, crowd-pleasing dessert that looks impressive but is simple to assemble.

Why You’ll Love This Chocolate Iced S’mores Cake

  • True s’mores flavor – Graham base, rich chocolate, and toasted marshmallows in one bite.
  • Sheet cake style – Baked in one pan and easy to slice and serve.
  • Gooey + fudgy – Moist chocolate cake with a shiny chocolate icing layer.
  • Great for a crowd – Serves a bunch and travels well.
  • Campfire vibes, no fire pit needed – Get that toasty marshmallow top right in your oven.

Ingredients

For the Graham Cracker Base

  • 200 g (about 2 cups) graham cracker crumbs (or digestive biscuits, finely crushed)
  • 80 g (6 tbsp) unsalted butter, melted
  • 2 tbsp granulated sugar
  • Pinch of salt

For the Chocolate Cake

  • 200 g (1½ cups) all-purpose flour
  • 60 g (1/2 cup) unsweetened cocoa powder
  • 1½ tsp baking powder
  • 1 tsp baking soda
  • 1/2 tsp fine salt
  • 200 g (1 cup) granulated sugar
  • 100 g (1/2 cup) packed light brown sugar
  • 120 ml (1/2 cup) neutral oil (vegetable, canola, or sunflower)
  • 2 large eggs, at room temperature
  • 1 tsp vanilla extract
  • 240 ml (1 cup) buttermilk, at room temperature
  • 120 ml (1/2 cup) hot coffee or hot water (for extra moisture and depth)

For the Chocolate Icing

  • 170 g (1½ cups) powdered sugar, sifted
  • 30 g (1/4 cup) unsweetened cocoa powder
  • 60 g (4 tbsp) unsalted butter, melted
  • 3–4 tbsp milk or cream (more as needed to thin)
  • 1 tsp vanilla extract
  • Pinch of salt

For the Toasted Marshmallow Topping

  • 250–300 g mini marshmallows (about 4–5 cups), or large marshmallows cut in half
  • Optional: extra crushed graham crackers and chocolate chips for sprinkling on top after toasting

Instructions

1) Prep the pan and graham base

Preheat your oven to 175°C (350°F).

Grease a 9×13-inch (23×33 cm) baking pan and line the bottom with parchment for easier removal, if desired.

In a bowl, mix graham cracker crumbs, melted butter, sugar, and a pinch of salt until the crumbs are evenly moistened.

Press firmly into an even layer over the bottom of the prepared pan.

Tip: Use the bottom of a measuring cup or glass to pack the graham layer tightly so it holds together when sliced.

2) Mix the dry cake ingredients

In a large bowl, whisk together flour, cocoa powder, baking powder, baking soda, and salt until well combined and no cocoa lumps remain. Set aside.

3) Mix the wet ingredients

In another large bowl, whisk granulated sugar, brown sugar, and oil until combined.

Add eggs and vanilla and whisk until smooth and slightly thickened.

Stir in the buttermilk until fully incorporated.

4) Combine the batter

Add the dry ingredients to the wet mixture and whisk gently until almost combined (a few small lumps are okay).

Slowly pour in the hot coffee or hot water while whisking on low until the batter is smooth and a bit thin.

Pour the chocolate cake batter over the graham base in the pan, spreading evenly to the corners.

5) Bake the cake

Bake at 175°C (350°F) for 28–34 minutes, or until a toothpick inserted into the center comes out with just a few moist crumbs (not wet batter).

Place the pan on a wire rack and let the cake cool completely in the pan before icing.

Tip: Don’t overbake—moist cake is key for that fudgy s’mores texture.

6) Make the chocolate icing

In a medium bowl, whisk together powdered sugar, cocoa powder, and a pinch of salt.

Add melted butter, vanilla, and 3 tbsp milk/cream. Whisk until smooth and glossy. If too thick, add a splash more milk, 1 tsp at a time; if too thin, add a little more powdered sugar.

Spread the chocolate icing in an even layer over the cooled cake.

7) Add and toast the marshmallows

Sprinkle mini marshmallows in a thick, even layer over the chocolate icing, covering the surface completely.

To toast:

  • Broiler method:
    Turn the oven broiler to high. Place the cake on a middle rack (not too close to the broiler). Broil for 30 seconds to 2 minutes, watching very closely until the marshmallows puff and turn golden brown with some deeper toasted spots.
  • Torch method:
    Use a kitchen torch to carefully toast the marshmallows until golden and lightly charred in spots.

Optionally, sprinkle a handful of extra graham crumbs and chocolate chips over the warm, toasted marshmallows.

Let the cake cool slightly so the topping can set before slicing (it will still be gooey and soft).

Serving Suggestions

  • Serve warm, slightly gooey, with cold milk, hot chocolate, or coffee.
  • Top slices with a scoop of vanilla or toasted marshmallow ice cream for an ultra-indulgent dessert.
  • Cut into smaller squares for party trays, bake sales, or potlucks.
  • For a cleaner slice, chill briefly, then bring back to room temperature before serving.

Cook’s Tips

  • Watch the broiler: Marshmallows go from golden to burnt in seconds—don’t walk away.
  • Use parchment: Lining the pan makes it easier to lift and slice neatly.
  • Neater slices: Lightly oil a knife or run it under hot water and wipe dry between cuts to avoid marshmallow sticking.
  • Layer balance: Don’t make the graham base too thick—a thinner base gives a better cake-to-graham ratio.
  • Coffee vs water: Hot coffee deepens the chocolate flavor but hot water works fine if you prefer no coffee.

Variations & Add-Ins

  • Extra chocolate chunks: Fold chocolate chips into the cake batter for pockets of melted chocolate.
  • Salted s’mores cake: Sprinkle a little flaky sea salt over the toasted marshmallow topping.
  • Peanut butter twist: Swirl a few spoonfuls of peanut butter into the icing before adding marshmallows.
  • Brownie base: Use a fudgy brownie batter instead of cake for a denser, richer dessert.
  • Individual minis: Bake the cake in lined cupcake tins (adjust baking time) and top each mini with marshmallows.

Storage & FAQ

  • Storage: Store leftover cake loosely covered at room temperature for 1–2 days, or in the fridge for 3–4 days. Marshmallows will soften over time but still taste great.
  • Reheating: For gooey marshmallows again, warm slices briefly in the microwave (5–10 seconds) before serving.
  • Freezing: Best enjoyed fresh, but you can freeze the cake (without marshmallow topping) wrapped well for up to 2 months, then thaw, ice, and add marshmallows before serving.
  • Can I use large marshmallows? Yes—cut them in half and place cut-side down for more coverage.
  • Cake too dry? Check your oven temperature and bake time; slightly underbaked is better than overbaked for this recipe.

Chocolate Iced S’mores Cake and Toasted Marshmallows gives you a full s’mores experience in sliceable form: graham base, moist chocolate cake, glossy icing, and a thick layer of toasted, gooey marshmallows. It’s nostalgic, dramatic, and guaranteed to be one of the first desserts to disappear from the table.

Chocolate Iced S’mores Cake and Toasted Marshmallows

Chocolate Iced S’mores Cake and Toasted Marshmallows
🖨 Print Recipe📌 Pin it
Servings: 12-16
Prep:
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A moist chocolate sheet cake baked over a buttery graham cracker base, topped with rich chocolate icing and a thick layer of toasted marshmallows. All the flavors of classic s’mores in an easy, crowd-friendly cake.

Chocolate Iced S’mores Cake and Toasted Marshmallows
🖨 Print Recipe📌 Pin it

Ingredients

  • Graham Cracker Base:
  • 200 g (about 2 cups) graham cracker crumbs
  • 80 g (6 tbsp) unsalted butter, melted
  • 2 tbsp granulated sugar
  • Pinch of salt
  • Chocolate Cake:
  • 200 g (1½ cups) all-purpose flour
  • 60 g (1/2 cup) unsweetened cocoa powder
  • 1½ tsp baking powder
  • 1 tsp baking soda
  • 1/2 tsp fine salt
  • 200 g (1 cup) granulated sugar
  • 100 g (1/2 cup) packed light brown sugar
  • 120 ml (1/2 cup) neutral oil
  • 2 large eggs, room temperature
  • 1 tsp vanilla extract
  • 240 ml (1 cup) buttermilk, room temperature
  • 120 ml (1/2 cup) hot coffee or hot water
  • Chocolate Icing:
  • 170 g (1½ cups) powdered sugar, sifted
  • 30 g (1/4 cup) unsweetened cocoa powder
  • 60 g (4 tbsp) unsalted butter, melted
  • 3–4 tbsp milk or cream
  • 1 tsp vanilla extract
  • Pinch of salt
  • Toasted Marshmallow Topping:
  • 250–300 g mini marshmallows (4–5 cups)
  • Optional: extra graham crumbs and chocolate chips for sprinkling on top

Instructions

  1. 1. Prepare pan and graham base
  2. 2. Preheat oven to 175°C (350°F). Grease a 9×13-inch pan and line the bottom with parchment if desired.
  3. 3. In a bowl, mix graham crumbs, melted butter, sugar, and a pinch of salt until evenly moistened.
  4. 4. Press firmly into an even layer in the pan.
  5. 5. Make the cake batter – dry ingredients
  6. 6. In a large bowl, whisk flour, cocoa powder, baking powder, baking soda, and salt. Set aside.
  7. 7. Make the cake batter – wet ingredients
  8. 8. In another bowl, whisk granulated sugar, brown sugar, and oil until combined.
  9. 9. Add eggs and vanilla and whisk until smooth.
  10. 10. Stir in the buttermilk until fully incorporated.
  11. 11. Combine and bake
  12. 12. Add the dry ingredients to the wet and whisk gently until almost smooth.
  13. 13. Slowly pour in the hot coffee or water, whisking until the batter is smooth (it will be thinner).
  14. 14. Pour batter over the graham base and spread evenly.
  15. 15. Bake for 28–34 minutes, or until a toothpick comes out with just a few moist crumbs.
  16. 16. Cool completely in the pan on a wire rack.
  17. 17. Make the chocolate icing
  18. 18. In a medium bowl, whisk powdered sugar, cocoa powder, and a pinch of salt.
  19. 19. Add melted butter, vanilla, and 3 tbsp milk/cream. Whisk until smooth and glossy, adding more milk as needed for a spreadable consistency.
  20. 20. Spread evenly over the cooled cake.
  21. 21. Top with marshmallows and toast
  22. 22. Sprinkle mini marshmallows in a thick, even layer over the iced cake.
  23. 23. Turn oven to broil and place the cake on a middle rack.
  24. 24. Broil for 30 seconds to 2 minutes, watching constantly, until marshmallows are puffed and golden brown with some deeper toasted spots.
  25. 25. (Alternatively, use a kitchen torch to toast.)
  26. 26. Cool slightly and serve
  27. 27. Allow the cake to cool slightly so the marshmallow topping sets a bit.
  28. 28. Slice with a lightly oiled or warm knife, wiping between cuts, and serve.

Notes

Keep a close eye on the marshmallows under the broiler; they toast very quickly.
For extra s’mores flair, sprinkle more graham crumbs and chocolate chips over the freshly toasted marshmallows.
For very clean slices, chill the cake briefly, then bring back toward room temperature before serving.
If you prefer less sweetness, reduce the icing slightly or use a thinner layer.

Nutrition

Calories: ~350–380
Protein: ~4–5 g
Total Fat: ~16–18 g
Carbohydrates: ~48–52 g
Fiber: ~2 g