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Mars Bar Cake Recipe

Published: Updated:
Quick and easy

59 Reviews

Prep Time
Serves 16
Serves 16

About our Mars Bar cakes:

Try baking our Mars Bar cakes for a slice of nostalgia. Not only is this recipe delicious, but it’s also fun and simple to make, and a perfect activity for you and your children. The chewy, gooey cereal base is blended with melted Mars Bars and topped with milk chocolate and white chocolate swirls. Bliss.

Can I melt Mars Bars in the microwave?

Yes, you can melt a Mars Bar in the microwave. We’d recommend you do this on the lowest power setting though, to avoid spoiling the chocolate. Put the Mars Bars in your microwave on a low setting, and check it every 30 seconds until it is melted and smooth.

Can I melt a Mars Bar on a hob?

If you don’t have a microwave, you can melt your Mars Bar in a small saucepan on the hob. Chop the Mars Bar into smaller chunks to speed up the melting process. Melt your chocolate on low heat and to check it often.

How to make sure your Mars Bar cakes are soft

If you haven’t melted and mixed your Mars Bars, syrup and butter enough, this can cause your final bake to turn out too hard and clumpy. When melting these three ingredients together, you can use a whisk as they begin to melt to get the mixture nice and smooth.

Reasons to make our Mars Bar cakes:

⭐Easy recipe for kids to follow (with supervision!)

⭐Can be made ahead of time and kept in the fridge

⭐Oven-free recipe

6 ingredients7 steps


    1. Step 1

      Lightly grease and line a 20cm square baking tin with greaseproof paper.

    2. Step 2

      In a heatproof bowl, melt and mix the butter, golden syrup and 3 of the chopped Mars Bars on a low heat. You want the resulting melted mix to be as smooth as possible.

      Ingredients for this step

      • Butter (unsalted, softened) (100g)
      • Mars Bar 40g size (chopped)  (4)
      • Silver spoon golden syrup (1 1/2 tbsp)
    3. Step 3

      Add the Rice Krispies into the heatproof bowl and stir in the remaining chopped Mars Bar which hasn’t been melted.

      Ingredients for this step

      • Rice krispies (150g)
      • Mars Bar 40g size (chopped)  (4)
    4. Step 4

      Pour the mixture into the baking tin and press down firmly (we used a potato masher for this to ensure there are no gaps and the top is nice and level).

    5. Step 5

      In another heatproof bowl, melt the milk chocolate, stirring until smooth, then pour over the top of the Krispie mixture.

      Ingredients for this step

      • Milk chocolate (350g)
    6. Step 6

      Moving quickly before the milk chocolate sets, melt the white chocolate and drizzle in lines up and down the surface of the Mars Bar slice. Using a skewer, drag forward and back through the mixture to create a feathered effect.

      Ingredients for this step

      • White chocolate (50g)
    7. Step 7

      Place the baking tin in the fridge to chill and set. Remove a little while before you plan to serve so that it is easier to cut into squares.


      • 100gButter (unsalted, softened) 
      • 4Mars Bar 40g size (chopped)  
      • 1 1/2 tbspSilver spoon golden syrup 
      • 150gRice krispies 
      • 350gMilk chocolate 
      • 50gWhite chocolate 


    • 20cm square baking tin
    • Parchment paper
    • Sharp knife
    • Heatproof bowl
    • Potato masher
    • Skewer

    Nutritional information per 50g serving

    • Energy 262cal
    • Fat 15g
    • of which Saturates 8.7g
    • Carbohydrates 29g
    • of which Sugars 22g
    • Protein 2.9g
    • Salt 0.21g

    59 Baker Ratings


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    Hubby can’t stop eating this- it has relaxed all other chocolate treats 🤣

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