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S’mores Sheet Cake

  • Author: shaemakes
  • Prep Time: 90 minutes
  • Cook Time: 35 minutes
  • Total Time: 2-2 1/2 hours
  • Yield: 24 1x


Homemade graham cracker cake base frosted with toasted marshmallow frosting made from actual roasted marshmallows and then topped with chocolate ganache and an addicting graham cracker “crack”.



For the cake:

  • 1 1/2 cups all purpose flour
  • 1 1/2 cups graham cracker crumbs
  • 1 1/2 tsp baking powder
  • 3/4 tsp baking soda
  • 3/4 tsp salt
  • 3/4 cup sour cream (room temp)
  • 1 tbsp vanilla extract
  • 3 tbsp vegetable oil
  • 2 1/4 sticks salted butter (softened)
  • 3/4 cup sugar
  • 3/4 cup brown sugar
  • 4 eggs (room temp)
  • 3/4 cup buttermilk (room temp)

For the frosting:

  • 24 large marshmallows
  • 1 1/2 cups powdered sugar
  • 3 sticks salted butter (softened)
  • 1 tsp vanilla extract
  • 1 1/2 jars marshmallow cream (roughly 1011 oz)

For the ganache:

  • 2 cups semi sweet chocolate chips
  • 1 cup heavy whipping cream

For the “crack”:

  • 24 graham cracker sheets
  • 3 sticks salted butter, melted
  • 2/3 cup brown sugar + 1/2 cup reserved
  • 1/4 tsp salt


For the “crack”:

  1. Preheat your oven to 400 degrees.
  2. Break up your graham crackers into roughly quarter sized pieces.
  3. In a medium sized bowl mix together broken up graham crackers, melted butter, 2/3 cup brown sugar and salt. Stir to combine.
  4. Line a half sheet pan with tinfoil and spray with cooking spray.
  5. Evenly spread out the graham cracker mixture onto the pan. Sprinkle evenly with remaining 1/2 cup brown sugar.
  6. Bake for 10 minutes.
  7. At the 10 minute mark, turn your oven to broil and let the mixture get a toasty brown color. Don’t walk away from the oven at this point or look away from your mixture while it is in the oven. It’ll burn in the matter of seconds so keep a close eye on it. It should only take like 60 seconds are so!
  8. Remove from the oven and let cool completely.
  9. Once cool, break mixture into small chunks and set aside while you make the cake.

For the cake:

  1. Preheat your oven to 350 degrees.
  2. In a stand mixer or with a hand mixer, cream together butter and sugars for 4 minutes until smooth.
  3. Add eggs one at time, scraping down the sides and bottom of the bowl after each addition.
  4. Mix for 2 minutes once all the eggs are added.
  5. Add vanilla, sour cream and oil and mix for an additional 2 minutes.
  6. In a separate medium sized bowl whisk together all dry ingredients.
  7. Alternating between the dry mixture and the buttermilk add them to the butter mixture, always starting and ending with the dry mixture. Mix until no flour streaks remain. Make sure and scrape down the sides and bottom of the bowl.
  8. Spray a half sheet pan liberally with cooking spray and pour cake batter evenly into the pan.
  9. Bake for 18-22 minutes or until a toothpick entered in the center comes out with a few moist crumbs on it.
  10. Set aside to cool while you make the frosting.

For the frosting:

  1. Turn your oven to broil and line a half sheet pan with parchment paper.
  2. Spread marshmallows evenly onto the sheet pan and add them to the hot oven. Do not walk away! Watch the marshmallows and roast them until they turn a nice dark golden brown on top. Remove the pan, flip the marshmallows over with tongs and repeat the roasting process. They should be nice and toasted on both sides.
  3. Set aside to cool slightly while you prepare the rest of the frosting.
  4. In a stand mixer or with a hand mixer, mix together butter and powdered sugar until smooth. Add vanilla and marshmallow cream and mix on medium high until light and fluffy, about 2 minutes.
  5. With your mixer on medium speed, slowly add your slightly cooled toasted marshmallows to the mixture a few at a time.
  6. Once they are all added beat the frosting on high speed for 2 minutes until everything is homogeneous.

For the ganache:

  1. In a microwave safe dish, heat cream for 60-90 seconds in the microwave.
  2. Pour hot cream over the chocolate chips and let them sit for 5 minutes.
  3. After 5 minutes stir together the cream and chocolate until completely smooth. (You may have to heat the mixture for an additional 30 seconds or so to get everything completely melted).


  1. Frost the cooled cake with the toasted marshmallow frosting.
  2. Evenly spread the chocolate ganache over top of the marshmallow frosting.
  3. Sprinkle the “crack” evenly over top of the ganache.
  4. Serve immediately, or store in the refrigerator for 2 hours for a more “set” cake.
  5. Store any leftovers in the fridge for up to 5 days.
  • Category: Dessert

Keywords: S'mores, Marshmallow, Sheetcake, Cake, Dessert