Mars Bar Slice is one of those classic Aussie treats everyone remembers from childhood – rich, chewy, chocolatey, and so easy to make. With just 5 ingredients and 10 minutes prep, this no-bake slice is perfect for parties, lunchboxes, or a sneaky treat with your cuppa.
Love old-school favourites? Try my Chocolate Coconut Slice or No-Bake Hedgehog Slice too!
I made the Mars Bar Slice (doubled the recipe) for all the boys at work. OMG!!!! It was gone in seconds! Thank you.
- Nerida
There’s something about melted Mars Bars, butter and golden syrup mixed through crispy rice bubbles and topped with a thick layer of milk chocolate… it’s the perfect combo of chewy, crunchy, and chocolatey. Sweet but not over-the-top, and incredibly simple to make – this slice is a total favourite in our house.
And with both Thermomix and conventional methods included, you can whip it up whichever way suits you best.
If you’re into quick no-bake slices like this, you’ll love my Clinkers Slice, Caramel Hedgehog Slice or Caramello Slice too!
Why You're Going To Love This Recipe
✔️ Just 5 ingredients and 10 minutes prep
✔️ No oven required – simply melt, mix, and chill
✔️ Includes Thermomix and stovetop instructions
✔️ Kid-approved for lunchboxes and birthday parties
✔️ Freezer-friendly for make-ahead treats
Jump to:
Slice Ingredients
Note: Scroll to the recipe card at the bottom for the ingredients quantities and full detailed method.
You only need a handful of simple ingredients – here are the key ones to get right:
- Mars Bars – Stick with the original for that signature flavour and chewy texture.
- Golden Syrup – Gives the slice its rich, sticky sweetness (see substitutions below).
- Rice Bubbles – Use a fresh box so the slice stays light and crunchy.
Variations
Love a twist on a classic? Try one of these easy Mars Bar Slice variations:
- Extra Caramel Kick: Drizzle over a little caramel sauce before adding the melted chocolate layer.
- Gluten-Free: Use gluten-free puffed rice and double-check all your chocolate is GF.
- Dark Chocolate Topping: Swap the milk chocolate for dark if you like it less sweet.
- Rocky Road Style: Mix through mini marshmallows and crushed nuts before pressing into the tin.
How To Make Mars Bar Slice
This slice is so easy – just melt, mix, chill… and devour!
Note: Scroll to the recipe card at the bottom for the ingredients quantities and full detailed method.
- Step 1: Melt the base
In a saucepan (or microwave-safe bowl), melt the butter, ⅔ of the chopped Mars Bars and golden syrup over low heat. Stir until smooth – don’t worry if some Mars Bar chunks remain.
- Step 2: Mix it up
Add the rice bubbles and the remaining Mars Bar chunks. Mix until well coated.
- Step 3: Press into tin
Spoon into the tin and press the mixture down VERY firmly – this helps it hold together once set.
- Step 4: Melt chocolate
In the microwave or over a double boiler, melt the milk chocolate with the coconut oil (if using), stirring until silky smooth.
- Step 5: Pour & chill
Spread the chocolate evenly over the base and chill in the fridge for at least 3–4 hours (overnight is ideal!).
Top Tip
Remove the slice from the fridge 30 minutes before cutting. Use a warm serrated knife to slice the Mars Bar Slice cleanly without cracking the chocolate layer!
Recipe Tips
- Use fresh rice bubbles so the slice stays crunchy and doesn’t go soggy.
- No golden syrup? Swap it for honey or maple syrup in a pinch – just know it’ll have a slightly different flavour and may be a little less chewy.
- Don't over-melt the Mars Bars – it’s fine if a few chunks remain.
- Press the mixture firmly into the tin – use the back of a spoon or even a glass to compact it.
- Coconut oil or vegetable oil helps prevent the chocolate layer from cracking when sliced.
- Let it set properly – chill for at least 3-4 hours, but overnight is best.
- Bring to room temp before slicing – this helps the chocolate soften just enough.
- Store in the fridge in an airtight container for up to 1 week.
Mars Bar Slice FAQs
Yes! Wrap individual pieces and freeze in an airtight container for up to 1 month. Perfect for lunchbox fillers or last-minute guests.
That’s totally normal! Mars Bars have nougat which doesn’t completely melt – you’ll get a gooey, sticky mix with some chewy bits, and that’s what you want.
It’s optional but helps keep the chocolate layer from cracking when you slice. You can skip it if you don’t have any.
Absolutely! Just use gluten-free puffed rice and check your Mars Bars and chocolate are certified GF.
Yes! If you don’t have golden syrup, you can substitute it with corn syrup, honey, or maple syrup. Keep in mind, golden syrup gives the slice its classic caramel flavour and stickiness, so other options may slightly change the taste and texture.
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Mars Bar Slice
Ingredients
- 75 g (⅓ cup) butter
- 150 g Mars Bars chopped
- 1 tbs (20g) golden syrup
- 3 cups (90g) rice bubbles or any puffed rice
- 250 g (1 ⅔ 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
- Use fresh rice bubbles so the slice stays crunchy and doesn’t go soggy.
- No golden syrup? Swap it for honey or maple syrup in a pinch – just know it’ll have a slightly different flavour and may be a little less chewy.
- Don't over-melt the Mars Bars – it’s fine if a few chunks remain.
- Press the mixture firmly into the tin – use the back of a spoon or even a glass to compact it.
- Coconut oil or vegetable oil helps prevent the chocolate layer from cracking when sliced.
- Let it set properly – chill for at least 3-4 hours, but overnight is best.
- Bring to room temp before slicing – this helps the chocolate soften just enough.
- Store in the fridge in an airtight container for up to 1 week.
Maria says
im wondering ifi the owner ot thermobliss and bakeplaysmile are the sam, because i see that the recipe its exactly the same with the only difference the coconut oil in the chocolate
Lucy Mathieson says
Hi Maria, I own half of ThermoBliss with my very good friend Lauren (who also owns a website called Create Bake Make). So yes!!! I'm both here and over at ThermoBliss!!!
Alicia says
Is this recipe suitable for freezing? I’d prefer not to but just wanted to check!
Lucy Mathieson says
Hi Alicia, yes you can freeze this recipe. xx
John Malcon says
Hello, Lucy!
Thank you for the perfect recipe! I sent to my wife a link on your blog!
John
Weedit.photos
Lucy Mathieson says
Thank you!!!
Lily says
Hello hello - me again - how long will it last in the fridge???
Lucy Mathieson says
Hi again! Up to 5 days 🙂
Tracey says
Coming from the uk I was wondering if you can tell me how many grams is in a cup? Love the sound of the mars bar slice as it's one of my favourite chocolate bars
Oh & seeing as you like Turkish Delight you might want to try these - Turkish Dekight Rocky Roads
Ingredients
100g butter, roughly chopped
300g dark chocolate, broken into squares
3 tbsp golden syrup
140g rich tea biscuit, roughly crushed
12 pink marshmallow, quartered (use scissors)
2 x 55g bars Turkish delight, halved and sliced
Method
Gently melt the butter, chocolate and syrup in a pan over a low heat, stirring frequently until smooth, then cool for about 10 mins.
Stir the biscuits and sweets into the pan until well mixed, then pour into a 17cm square tin lined with foil and spread the mixture to roughly level it. Chill until hard, then cut into fingers.
Bake Play Smile says
Yum sounds delicious!! You might find this website helpful for converting ingredients: http://dish.allrecipes.com/cup-to-gram-conversions/