Mars Bar Tray Bake Cake (No-Bake)

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This no-bake Mars Bar tray bake is made with golden syrup and crispy cereal to make a quick and easy dessert. It's a gooey, crunchy and chocolatey cake slice, and it's ideal for sharing at any special occasion!

stack of mars bar tray bake squares on a plate

If you like no-bake tray desserts then you're going to LOVE this Mars Bar tray bake! With just 5 simple ingredients, you can whip this up to feed a small crowd in less than a couple of hours.

Mars Bar tray bake, or Mars Bar slice, is a chocolate caramel crispy "cake". Despite what the name may suggest, there's actually no baking needed for this recipe. You just melt, mix and refrigerate!

This no-bake cake is said to have first been created in Australia but it has since become super popular in the UK too. Some people make it with digestive biscuits, which produces something more similar to a Scottish tiffin, but I like to make mine with Rice Krispies or Coco Pops for that added crispy texture. You can think of it as a homemade version of chocolate caramel Rice Krispie squares!

Keep reading below for my top tips, ingredient notes, step-by-step images and more. And if you like this recipe, make sure to check out my Mars Bar cookies, blondies and brownies too. Enjoy!

Ingredients

Here's everything you'll need to make this crispy traybake:

Butter: Any kind of butter or margarine will work fine here. I like to use salted butter as it helps to cut through the sweetness a little.
Golden Syrup: Golden syrup is a thick, sweet, sticky liquid that helps to bind the rest of the ingredients together. It's best to use this if you can, but an equal amount of honey or agave nectar can work in a pinch.
Mars Bars: In grams, the total weight of the Mars Bars should be roughly 200g. That's 4 full-size bars, 5 multipack-size bar, or 11 fun-size bars.
Crispy cereal: Most other recipes are made with Rice Krispies but I have always used Coco Pops in mine because I just love chocolate so much! Either will work fine, it just depends on your preference and whatever you have at home.
Chocolate: Last but not least is some chocolate for the topping. You can use milk, white or dark chocolate, depending on how sweet you want it. You can even use a mixture of different types of chocolate and marble them together to make a pattern. I personally like milk chocolate on mine.

Equipment

8x8-inch tin: This size of tin will give you 16 decently-thick slices. If you want to use a different tin, I'd recommend using my cake pan converter to adjust the recipe to fit.
Baking paper: To prevent sticking. Leaving a little bit hanging over the edges will make it easier to lift the tray bake out later.
Saucepan: To melt the Mars Bars with the butter and syrup.
Wooden spoon or spatula: For mixing everything together.
Mixing bowl: A large one.
Heatproof bowl: To melt the chocolate for the topping (or you can use your saucepan again if you prefer).

stack of 2 pieces of mars bar traybake slice

How to make Mars Bar tray bake cake

Step 1: Line an 8x8-inch tin with baking paper. Set it aside for now.

Step 2: Chop 4 full-size Mars Bars into small pieces then add them to a saucepan along with 100g of butter and 2 tablespoons of golden syrup.

Step 3: Place the saucepan over low heat and stir occasionally until everything has melted. There may be a few small lumps of Mars Bar that don't completely melt but don't worry!

Step 4: Place 130g of Coco Pops or Rice Krispies into a large mixing bowl then pour in the melted Mars Bar mixture. Mix well until all of the cereal is evenly coated.

coco pops and melted chocolate in a bowl

Step 5: Transfer the mixture to your lined tin and press it firmly into place. I like to use the bottom of a measuring cup to do this, but you can use your hands if you prefer.

caramel cereal mixture pressed into a lined tin

Step 6: Melt 250g of milk chocolate. You can do this in a saucepan over the stove or in small bursts in a heatproof bowl in the microwave.

Step 7: Pour the melted chocolate over the tray bake and spread it out evenly. Place the whole thing in the fridge for 2 hours until the layer of chocolate on top has set.

Step 8: Once set, remove it from the tin using the baking paper. Cut into 16 equal-sized squares and enjoy!

Top tips

Use a low heat when melting the ingredients. Make sure to stir occasionally to prevent burning.
Use a scale to measure the butter and cereal accurately. This will ensure your Mars Bar slice isn't too crumbly nor too sticky.
Press the cereal mixture firmly into the tin. This will help to keep it intact when you cut into it.
To prevent the topping from cracking when you cut into it, use a warm knife. You can warm your knife by dipping it into boiling water and drying it immediately before cutting. Repeat before each slice.

FAQs

How long does Mars Bar tray bake last?

This crispy dessert will last for at least a week if stored in an airtight container in the fridge. This makes it great for preparing in advance for parties or bake sales!

Can I freeze this recipe?

Yes, for up to 3 months. After it's fully set, you can wrap the whole slab tightly in clingfilm or put slices into airtight containers. When you're ready to defrost it, letit set at room temperature for an hour or so, or pop it in the fridge overnight. Do not refreeze.

Why did my traybake crack?

This can happen due to the hard chocolate topping. You can ensure a crack-free slice by warming the knife in boiling water and quickly drying it before making your cuts. You can also add a teaspoon of coconut oil to the chocolate topping to help soften it a little bit.

3 slices of no bake mars bar cake on a plate

More no-bake tray bake recipes:

I hope you like this Mars Bar tray bake! If you enjoy the recipe, please leave a comment below to let me know. Enjoy!