Mars Bar Slice | 10 Minute Recipe

Everyone’s favourite no-bake Mars Bar Slice recipe couldn’t be easier to make… with just 5 ingredients and 10 minutes prep time. This crunchy chocolate caramel rice bubble slice recipe is always the most popular sweet treat in lunchboxes, at morning teas or bake sales.

A plate of pieces of chocolate caramel rice bubble slice topped with milk chocolate

It’s no secret that no-bake slices hold a special place in my sweet-filled heart. Not only are they quick, easy and completely foolproof, they’re also absolutely delicious!

In my list of the top 5 most popular no-bake slice recipes, Mars Bar Slice is right up there – along with Lemon & Coconut Slice, Jelly Slice, Clinkers Slice and Peppermint Slice

Mars Bar Slice Recipe

With it’s sweet and crunchy chocolate caramel rice bubble base and milk chocolate topping, it doesn’t get any more delicious than this 10 minute recipe. 

Forget any fancy equipment, all you need to make this slice is a microwave (or stovetop or Thermomix), a bowl and spoon. That’s it!

Let me tell you… if you love Mars Bars, then this slice is going to become your number 1 favourite recipe.

Pieces of crunchy rice bubble slice made with chocolate and caramel and topped with milk chocolate on a plate

What You Need

*Please scroll to the recipe card at the bottom of the post for ingredient quantities and the full detailed method

All you need is just 5 ingredients: 

  • butter – either unsalted or salted butter can be used
  • Mars Bars – are a chocolate bar produced by Mars that have layers of nougat and caramel, coated in milk chocolate
  • rice bubbles (or any puffed rice) – also known as rice krispies
  • golden syrup – is a popular baking ingredient in Australia. It is a light thick and sticky sweet treacle. If you can’t find golden syrup in your supermarket, you can substitute it for corn syrup, honey or maple syrup.
  • milk chocolate – choose a good quality cooking chocolate as it will melt easily when heated. I generally use Cadbury or Nestle cooking chocolate or melts.
  • coconut oil or vegetable oil – this is an optional step but by adding coconut oil or vegetable oil to the melted chocolate, it will make the chocolate easier to cut once set.
Bowls of rice krispies, chopped Mars bars, butter and golden syrup on a marble mat.

10 Minute Recipe

*Please scroll to the recipe card at the bottom of the post for ingredient quantities and the full detailed method

Step 1 – Melt

Chop the Mars Bars into small chunks, add the butter and golden syrup and melt in a heatproof bowl in the microwave on low heat (or on the stovetop/Thermomix).

Chopped Mars Bars, butter and golden syrup in a white bowl.

Note: The Mars Bars will not melt entirely – they will still be a little chunky which gives the slice a delicious texture and taste.

Melted Mars Bars, butter and golden syrup in a white bowl.

Step 2 – Mix

Add the remaining chunks of Mars Bar pieces and the rice bubbles (rice krispies) and stir through with a metal spoon. The liquid will cover the rice bubbles making it a sticky mixture.

Rice krispies and chopped Mars Bars in a white bowl.
Sticky chocolate, caramel and rice bubble mixture in a white bowl.

Step 3 – Press Into Tin

The trick to the perfect Mars Bar slice is to press the mixture very firmly into a prepared baking paper lined rectangular slice tin (approximately 18cm x 22cm).

I recommend either pressing the mixture down with a round glass or placing a tin of the same size on top and pressing down firmly until there’s no loose rice bubbles remaining.

Chocolate rice bubble slice mixture pressed into a baking paper lined rectangular tin.

Step 4 – Add The Melted Chocolate

You can melt the chocolate in the microwave or on the stovetop (or in a Thermomix).

I recommend using cooking chocolate or chocolate baking melts as they melt easier.

See my tips for melting chocolate in the microwave here.

Melted milk chocolate being poured on top of a chocolate rice bubble base.

Step 5 – Refrigerate

It’s important to allow the slice to set in the fridge before attempting to cut it.

If time allows, it’s best to leave it in the fridge overnight before cutting. If you’re pushed for time, refrigerate for at least 3-4 hours.

Melted chocolate spread over a no-bake chocolate, caramel and rice bubble slice in a baking tin.

Recipe Tips

  • You can melt the butter, golden syrup and Mars Bars in the microwave, on the stove-top or in a Thermomix.
  • Make sure you use a fresh box of rice bubbles or rice krispies – this will ensure your slice is crispy and crunchy!
  • The Mars Bars will not melt completely but will remain in small chunks – this is fine and gives the slice it’s classic chunky texture.
  • Press the mixture firmly into a greased and lined baking tin. The mixture needs to be pressed down very firmly so that it doesn’t break apart when you cut it.
  • Adding coconut oil or vegetable oil to the milk chocolate will help it to stop from cracking when sliced. 
  • Leave in the fridge to set for a minimum of 3-4 hours (overnight is best). 
  • Take the slice out of the fridge 30 minutes before cutting to allow the chocolate to soften slightly. 
  • Use a small serrated knife to cut through the chocolate layer and then through the rice bubbles layer. 
Pieces of chocolate slice made with Mars Bars and rice bubbles and topped with milk chocolate on a copper wire tray

Storing Mars Bar Slice

Mars Bar Slice can be stored in an airtight container in the fridge for up to 1 week. It can also be frozen for up to 1 month. 

More Mars Bar Recipes

If you love Mars Bars (and who doesn’t!) check out these delicious recipes:

FAQ

What can I substitute the golden syrup for?

You can replace the golden syrup with corn syrup, honey or maple syrup. 

What are Mars Bars?

Mars Bars are a nougat and caramel bar covered in chocolate. They are made by Mars can be purchased from any supermarket. 

How can I stop my slice from cracking and breaking when I cut it?

Make sure the mixture has been very firmly pressed into the tin. Leave it to set in the fridge for a minimum of 3-4 hours (but overnight is best). Take the slice out of the fridge for 30 minutes before cutting. Use a small serrated knife to gently cut through the chocolate layer. Adding coconut oil or vegetable oil to the melted chocolate will also prevent cracking. 

Are Mars Bars and Milky Ways the same?

No they’re not. Mars Bars have layers of caramel and nougat covered in milk chocolate. Milky Ways are similar but they don’t have the caramel layer. You can substitute Mars Bars for Milky Ways or Moro bars in Mars Bar slice if you prefer (although my favourite version is definitely with Mars Bars!)

Can I make Mars Bar slice in my Thermomix?

Absolutely – refer to the recipe card below for the conventional and Thermomix methods. 

Can you freeze Mars Slice slice?

Yes! Cut the slice into pieces and then freeze in an airtight container for up to 3 months. To defrost, remove from the freezer and place in the fridge for an hour or until defrosted. If you prefer, you can even eat it directly from the freezer for a delicious crunchy, cold summer treat!

Can you add marshmallows to Mars Bar slice?

I love adding mini marshmallows to my Mars Bar slice. Simply chop marshmallows into little pieces or use mini marshmallows and stir through at the same step as the rice bubbles (rice krispies). Make sure your marshmallows are small so that it’s easy to cut your slice into pieces.

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Mars Bar Slice

Mars Bar Slice

Everyone's favourite no-bake Mars Bar Slice recipe couldn't be easier to make… with just 5 ingredients and 10 minutes prep time.
5 from 3 votes
Print Pin Rate
Course: bars and slices
Cuisine: American, Australian recipe, western
Keyword: mars bar slice
Prep Time: 10 minutes
Chilling time: 4 hours
Total Time: 4 hours 10 minutes
Servings: 20 serves
Calories: 151kcal

Ingredients

  • 75 g (1/3 cup) butter
  • 150 g Mars Bars chopped
  • 1 tbs (20g) golden syrup
  • 3 cups (90g) rice bubbles or any puffed rice
  • 250 g (1 2/3 cups) milk chocolate
  • 1 tbs (20g) coconut oil or vegetable oil (optional)

Instructions

Conventional Method

  • Grease and line a 18cm X 22cm rectangular slice tin with baking paper and set aside. 
  • Melt the butter, 100g (two thirds) of the Mars Bars and golden syrup on low heat in a saucepan (or in 30 second bursts in the microwave on 50% power). Please note: the Mars Bars will not completely melt. Mix until the butter and golden syrup are smooth.
  • Stir through the rice bubbles and the remaining Mars Bar (chopped).
  • Press mixture very firmly into the prepared tin. 
  • Place milk chocolate and coconut oil/vegetable oil in a heatproof bowl. Microwave on medium for 3 minutes, 50% power, or until just melted, stirring every 30 seconds with a metal spoon. Stir until smooth.
  • Spread over slice and refrigerate until firm (a minimum of 3-4 hours – or best overnight).
  • Remove slice from the refrigerator about 30 minutes before cutting into squares with a warm serrated knife.

Thermomix Method

  • Grease and line a 18cm X 22cm rectangular slice tin with baking paper and set aside. 
  • Place 100g (two thirds) of the chopped Mars Bars, butter and golden syrup into the Thermomix bowl. Melt on 60 degrees, Speed 2 for 3 minutes.
  • Add the rice bubbles and the remaining Mars Bar. Mix on Reverse, Speed 2, 15 seconds or until completely combined.
  • Press the mixture very firmly into the prepared tin.
  • Place the milk chocolate into a clean TM bowl. Melt on 50 degrees, Speed 3 for 2-3 minutes (scraping down the sides of the bowl occasionally).
  • Spread over slice and refrigerate until firm (a minimum of 3-4 hours – or best overnight).
  • Remove slice from the refrigerator about 30 minutes before cutting into squares with a warm serrated knife.

Notes

Recipe Notes
Melting the butter, golden syrup and Mars Bars – you can melt the ingredients in the microwave, on the stove-top or in a Thermomix. Note: The Mars Bars will not melt completely but will still in small chunks – this is fine. 
Use a fresh box of rice bubbles or rice krispies – this will ensure your slice is crispy and crunchy!
Press the mixture VERY firmly into a greased and lined baking tin – The mixture needs to be pressed down very firmly so that it doesn’t break apart you you cut it.
Adding coconut oil or vegetable oil to the milk chocolate – will help it to stop from cracking when sliced. 
Setting time – Leave in the fridge to set for a minimum of 3-4 hours (overnight is best). 
Cutting the slice – Take the slice out of the fridge 30 minutes before cutting to allow the chocolate to soften slightly. Use a small serrated knife to cut through the chocolate layer and then through the rice bubbles layer. 
Storing the slice – Mars Bar Slice can be stored in an airtight container in the fridge for up to 1 week. It can also be frozen for up to 1 month. 
Golden syrup substitutions – You can replace the golden syrup with corn syrup, honey or maple syrup. 
 

Nutrition

Calories: 151kcal | Carbohydrates: 15g | Protein: 1g | Fat: 11g | Saturated Fat: 7g | Cholesterol: 8mg | Sodium: 30mg | Potassium: 61mg | Fiber: 1g | Sugar: 11g | Vitamin A: 95IU | Calcium: 6mg | Iron: 0.6mg
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52 Comments
  1. Julia says:

    How long will this keep in the fridge?

    1. Lucy says:

      Hi Julia, up to 1 week xx

  2. Carmel McArthur says:

    Can I use dark chocolate instead of milk chocolate for the topping? Thank you

  3. Susan says:

    Look delicious! Would it be gluten free?

    1. Lucy says:

      Hi there, you would need to use gluten-free puffed rice xx

  4. Una Robinson says:

    Hia I don’t have golden syrup, could I use maple syrup instead?

    1. Lucy says:

      Hi Una, sure! Or honey!

  5. Glyn says:

    Can I substitute coconut oil for the butter?

    1. Lucy says:

      Hi Glyn, hmmm I havent actually tried that sorry!

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