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Unicorn Weetbix Marshmallow Slice

This Unicorn Weetbix Marshmallow Slice is the perfect sweet addition to any Unicorn themed party.


It’s safe to say the internet has gone unicorn mad right now.  There are colourful unicorn recipes everywhere I look, and anything unicorn related on our website in incredibly popular.  I decided to try turning our ever popular Weetbix Marshmallow Slice into this layered Unicorn Weetbix Marshmallow Slice and it turned out better than I had hoped.  There is the extra step of separating the marshmallow and colouring it in 3 batches, but the results are well worth the effort.


Check out our other unicorn recipes:


The first step to making this delicious slice is to make the Weetbix base.  First, pre heat the oven to 180c and line a slice tin with baking paper.  Add the butter to a large microwave safe mixing bowl and melt in the microwave.  Next, add the crushed Weetbix, self raising flour, brown sugar, coconut and vanilla extract.  Mix until all ingredients are well combined.  Press the mixture firmly into the prepared slice tin and bake in the oven for 15 minutes.  Remove from the oven and set aside to cool.

Once the base has cooled, it’s time to make a start on the marshmallow.  Add the cold water and sugar to the bowl of a stand mixer with a wire whisk attachment, and whisk for around 3 minutes.  Dissolve the powdered gelatine in the boiling water and add to the stand mixer.  Continue whisking until the mixture is thick and white, which could take up to 8 minutes.


Once the marshmallow is ready, divide it into 3 small bowls.  Add a little of the food colouring to each bowl, and mix until evenly coloured.  Spread the coloured marshmallow over the slice base, one colour at a time.  Place in the fridge for an hour to set, before slicing and serving.


This Unicorn Weetbix Marshmallow Slice is the perfect sweet addition to any Unicorn themed party.

Unicorn Weetbix Marshmallow Slice


  • 3 Weetbix, crushed
  • 1 cup desiccated coconut
  • 1 cup self raising flour
  • 1/2 cup brown sugar
  • 1 teaspoon vanilla extract
  • 150g butter, melted
  • 1/3 cup cold water
  • 1 cup sugar
  • 1/3 cup boiling water
  • 1 tablespoon gelatine
  • pink, purple and teal food colouring


Preheat oven to 180c. Line a slice tin with baking paper.
Add Weetbix, coconut, flour, brown sugar, vanilla and butter to a large bowl and stir until well combined. Press the mixture into the slice tin, and bake for 15 minutes.
While the base is cooking, place the cold water and sugar into a stand mixer with a whisk attachment and mix for 3 minutes. Combine the boiling water and gelatine with a fork, then add to the mixer. Beat for 8 minutes or until thick and white.
Separate the marshmallow into 3 bowls, colouring each with one of the 3 food colourings.
Spread the marshmallow on to the slice base, one colour at a time, and place in the fridge for an hour or so until set.

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Want more easy slice recipes like this one?  Download our free 17 easy slice recipes ebook, and get your hands on a copy of our recipe eBook, The Ultimate Easy Slice Handbook.

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