This one was just too good to keep to myself!

Picture this – layers of dense chocolate sponge, toasty chewy marshmallows, crunchy buttery biscuit and a smooth sweet buttercream.. wow.

I love this recipe so much, this cake is so well balanced and not too sweet at all!

I would love for you to try out this recipe and give me your feedback 🙂 <3 Sofia xxx


The ingredients below are given in cups as I didn’t weigh them into grams when I baked this cake (sorry!), but I will be updating the recipe in due course if you don’t like using cup measurements🙂

  • 2 cups all-purpose flour
  • 2 cups sugar
  • ¾ cup unsweetened cocoa powder
  • 2 teaspoons baking powder
  • 1½ teaspoons baking soda
  • 1 teaspoon salt
  • 1 teaspoon instant coffee
  • 1 cup milk
  • ½ cup vegetable oil
  • 2 eggs
  • 2 teaspoons vanilla bean paste/ extract
  • 1 cup boiling water
  • 600 icing sugar, sifted
  • 300g butter, softened
  • 2 tsbp. milk
  • 1 tsp.vanilla paste
  • 5 digestive biscuits
  • 1 bag of marshmallows
  • chocolate and optional extras to decorate


  1. Preheat your oven to 180°C, and grease two 8 or 9″ baking tins with butter.
  2. Place the flour, sugar, baking powder, baking soda, cocoa and salt into a large mixing bowl. Whisk to produce a uniform mix.
  3. Add your eggs, milk and vanilla to the dry ingredients and whisk well to combine.
  4. Finally, to one cup of boiling water, add the instant coffee and stir. Pour slowly into your mixing bowl and whisk to produce a thin chocolate batter mixture – the secret to this super moist cake!
  5. Pour evenly into your cake tins and bake in the oven for roughly 30mins, until the cakes are springy to the touch!
  6. Remove from the oven and allow to cool completely.
  7. Whilst your cakes cool, chop a handful of your marshmallows into small bite sized pieces, reserving the rest for decoration. Also, crush your digestive biscuits into small crumbs using a rolling-pin.
  8. Next, make the buttercream – Place your softened butter into a large bowl or into a free-standing mixer. Beat using a k-hook or use a handheld electric whisk. Sift half of the icing sugar into the butter, and whisk until combined. Add a tbsp. of milk, followed by the vanilla and whisk again. Sift in the remaining icing sugar and beat again. The buttercream should be silky and smooth – if yours feels too firm to spread, add some more milk 1 tbsp. at a time, until the consistency is correct.

Assembling your cake:

  1. Finally, fill and decorate your cake! Place one chocolate sponge in the middle of your plate or cake stand. Spread 1/4 of the butter on top of the cake. Sprinkle a 3/4 of the biscuit crumbs on top of the buttercream, followed by all of the marshmallow pieces, your cake will look extremely full and indulgent, yum.
  2. Place your other sponge on top of the cake and spread 1/3 of the remaining buttercream on top.
  3. With the buttercream that’s left, spread it evenly and gently around the perimeter of the cake, using an offset palette knife. Spread until all of the chocolate cake is covered – I kept an inch of the top of my cake exposed because I liked the way it looked, but feel free to design your cake in your own style🙂
  4. Lastly, decorate your cake with marshmallows, biscuit crumbs and melted chocolate!

With my leftover melted chocolate, I spread little lines onto the cake, and then with a cake scraper I gently dragged the chocolate-covered buttercream along the outside of the cake to create those ombre-chocolate tones❤

Enjoy! Sofia xxx

Notes – the chocolate sponge recipe is the best chocolate cake recipe from the amazing Add a Pinch blog, and its the only one I ever use🙂