This deliciously crispy Mars Bar Slice takes 10 minutes to prepare from 5 ingredients. It's a no-bake recipe that makes an excellent lunchbox or after-school treat.
Though Mars Bar Slice was first developed in Australia, it's now popular worldwide. Rice Bubbles / Rice Krispies are combined with melted Mars Bars and butter to form the crunchy base, then topped with a smooth layer of chocolate. It's a match made in heaven!
If you love a no-bake slice recipe, check out my classic Hedgehog Slice. An Aussie favourite made with chocolate, sweetened condensed milk, plain biscuits, desiccated coconut, butter and cocoa powder.
What are Mars Bars?
Mars Bars are a sweet treat originating in England. They're made with nougat, caramel, and chocolate, then covered in milk chocolate. They're known for their sweet taste and soft texture.
Why We Love This Recipe
- A no-bake recipe with 5 simple ingredients.
- Ten minutes to make with minimal preparation.
- It keeps well in the fridge or freezer.
Note: The full quantities are shown in the recipe card below.
Mars Bars - come in all shapes and sizes these days, depending on where you live. They also seem to have shrunk in size! I've put the measurement in weight in the recipe card.
Butter - use unsalted butter.
Rice Bubbles - called Rice Krispies in the UK, USA and elsewhere.
Milk chocolate - use baking chocolate melts. Excellent quality brands are Cadburys or Nestle. I don't recommend home-brand baking chocolate for this recipe, as the taste is not good. Also, it's essential not to use regular milk chocolate, as it won't set properly. You could use dark chocolate instead.
Vegetable oil - add a little to the melted chocolate to prevent the topping from cracking.
Step by Step Instructions
Note: This is a summary of the instructions. The full ingredients and instructions are shown in the recipe card below.
For the Base
Step 1. Line a square baking tin with baking paper, leaving a slight overhang on each side. The overhang makes it easy to lift the slice out of the baking tin once set.
Steps 2-3. Melt the Mars Bars and butter in the saucepan over medium to high heat. To prevent the mixture from burning, constantly stir until melted.
Step 4. Add the Rice Bubbles / Rice Krispies to a large bowl.
Step 5. Pour the melted mars bar mix over the Rice Bubbles / Rice Krispies and stir well until they are all coated.
Step 6. Press the mixture into the tin - take your time doing this, and don't forget the corners! Transfer to the fridge to set for a couple of hours before making the chocolate topping.
For the Chocolate Topping
Melt the chocolate in the microwave, stirring every 20-30 seconds (this ensures even melting). Stir in the vegetable oil once the chocolate melts. If you don't have a microwave, you could use the bain-marie method of melting chocolate in a bowl over a saucepan. See instructions here.
Pour the chocolate over the base, level with a spoon, then transfer it back to the fridge to set for 2-3 hours or overnight.
Take the Mars Bar Slice out of the fridge 30 minutes before serving. Cut into squares or slices with a warm knife.
FAQs & Expert Tips
Yes, you can! Swap with the same quantity of Rice Bubbles / Rice Krispies.
Vegetable oil added to the melted chocolate helps the chocolate not break. Also, warming a sharp knife in hot water before cutting it helps.
It will keep in the refrigerator for up to a week - if it lasts that long!
Yes, the Mars Bar Slice will keep in the freezer for up to 1 month.
Leave it to soften at room temperature on the benchtop half an hour before consuming.
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Mars Bar Slice
- 20cm (8") square baking tin.
- 190 g Mars Bars, chopped into small pieces, note 1
- 75 g unsalted butter, plus extra for greasing
- 110 g Rice Bubbles / Rice Krispies
- 250 g milk melting chocolate, or dark chocolate (US: semi-sweet chocolate chips) note 2
- 1 tablespoon vegetable oil, helps prevent the chocolate from cracking
For the Base
- Grease and line the base of a 20cm (8") square baking tin with baking paper. Leave some overhang on each side for ease of removal.
- Melt the Mars Bars and butter in a saucepan on the stovetop over medium to high heat and constantly stir until melted. The mixture will be smooth and shiny.
- Place the Rice Bubbles / Rice Krispies into a large bowl and pour the melted mixture over the top. Work quickly and stir together with a spoon until all the Rice Bubbles are coated. (see step by step photos in post).
- Firmly press the mixture into the baking tin and place it in the fridge to set for a couple of hours.
For the Chocolate Topping
- Melt the chocolate in the microwave, stirring every 20-30 seconds (this ensures even melting). Stir in the vegetable oil once the chocolate melts. If you don't have a microwave, you could use the bain-marie method of melting chocolate in a bowl over a saucepan. See instructions here.
- Pour the chocolate over the base, level with a spoon, and transfer it back to the fridge to set for 2-3 hours or overnight.
To Cut and Serve
- Take the Mars Bar Slice out of the fridge 30 minutes before serving. Cut into squares or slices with a warm knife.