Mars Bar Squares
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What do you get when you melt together chocolate bars and mix them with Rice Krispies? These delicious, no-bake Mars Bar Squares. They’re gooey, crunchy, topped with milk chocolate and absolutely addictive. You’ll love the chocolate caramel flavor.
**This post was updated July 29, 2025 with new photos and recipe tips. The much loved recipe is the same**
Mars bar squares are like chocolate Rice Krispie treats – only instead of melting together marshmallows, butter and chocolate, we’re using 4 whole Mars bars along with the butter. The nougat layer of the Mars bars adds gooiness, just like marshmallows. Then the milk chocolate and caramel give the most delicious flavor. I like to add an additional layer of milk chocolate on top, but that’s optional.
I always think of Mars bar squares as a summertime treat, because they’re no-bake and perfect for snacking on car rides. But they’re also great for using up leftover Halloween candy or whenever you’re craving something sweet. When living in Australia – they were usually called a Mars bar slice or even Mars bar Rice Bubble slice since Rice Krispies are called Rice Bubbles in Australia (who knew???)
Making the PERFECT Mars Bar Rice Krispie Treat
I always like to ensure the perfect ratio of chocolate bars to cereal so that my bars are a little gooey, but still hold together and are easy to slice. For the perfect ingredient ratios, I use:
- 1/2 cup unsalted butter (112 grams)
- 4 Mars bars (53 grams each)
- 3 cups Rice Krispies / Rice Bubbles
- 1 cup milk chocolate chips, or 200 g chopped milk chocolate for the topping
If you want your bars a little gooier, you could use 2 1/2 cups Rice Krispies.
In a large saucepan, you’ll first melt the butter over very low heat. Then add in the chocolate bars, chopped into small pieces. Gently stir the mixture as the bars begin to melt and ooze into the butter. It’s very important that the burner is on low heat, otherwise the caramel and chocolate can start to burn instead of melt.
Pro Tip: If the butter and melted chocolate bars are starting to separate as they melt, remove the pan from the heat and whisk vigorously.
Once totally melted, carefully stir in the cereal then press the mixture into a greased 8×8 inch (20×20 cm) pan. Technically, you could use a 9×9 inch pan, however, the bars will be quite a bit thinner.
Then a layer of creamy, melted milk chocolate goes on top and your bars are ready to set. I always let mine firm up at room temperature because when you put chocolate in the fridge to harden it can discolor and get those weird little white flecks on top.
Baking Tips & Tricks
- If you can’t find Mars bars, Milky Way bars work too.
- Feel free to use milk, semi-sweet or dark chocolate for the coating on top.
- For the topping – always melt chocolate in the microwave on medium power for 45-second intervals. Remove the bowl from the microwave and give the chocolate a stir in between each interval to prevent burning.
- When the chocolate topping is about 80% hardened, score the top of the bars with a thin, sharp knife. This prevents the chocolate cracking when you go to slice the bars.
- This recipe can be doubled and made in a 9×13 inch pan.
Or for more delicious no-bake slices and bars, be sure to try:
Mars Bar Squares
Equipment
- 8×8 inch (20×20 cm) pan
Ingredients
- 1/2 cup unsalted butter (112 grams)
- 4 Mars bars (53 grams each), chopped
- 3 cups Rice Krispies (about 90 grams) , aka Rice Bubbles
- 1 cup milk chocolate chips (about 200 grams), or chopped milk chocolate
Instructions
- Lightly grease an 8×8 inch (20×20 cm) square baking pan.
- Add the butter to a large saucepan and gently melt the butter over low heat.
- Add the chopped Mars bars to the butter and gently stir the mixture as the Mars bars begin to melt.
- Continuously stir the mixture until smooth. If the butter and chocolate bars start to separate, remove from the heat and whisk until smooth. Stir constantly to avoid burning.
- Once melted, turn off the burner and stir in the Rice Kripies/Rice Bubbles. Feel free to use 2 1/2 cups (instead of 3 cups) for gooier bars.
- Spoon the batter into the prepared pan, and gently press it down. You can lightly grease a spatula or spray your hands with non-stick cooking spray if you find the mixture keeps sticking to the spatula or your hands.
- Add the chocolate chips/chopped chocolate to a heatproof bowl. Microwave on medium power for 45-second intervals, stirring between each. Once the chocolate is almost melted, stir until smooth. Alternatively, melt in a double boiler over low heat. Ensure that the water underneath does not touch the bottom of the bowl with the chocolate.
- Spread the mixture over the bars and let sit for 2 hours at room temperature, or until the chocolate is hardened before slicing into bars. When the chocolate topping looks about 80% hardened, use a thin knife to trace along the top where you plan to slice the bars. This makes slicing easier because the chocolate topping won't crack.
Notes
- Rice Krispies: For gooier bars, use 2 1/2 cups Rice Krispies/Rice Bubbles.
- Storage: Store in an airtight container at room temperature for up to 4 days. I do not recommend storing in the fridge or freezing the bars because the chocolate topping can discolor, and they can end up getting too hard and crunchy. If you choose to freeze them, thaw in the fridge overnight then let them sit on the counter at room temperature before enjoying.
- Nutrition: Nutrition info is based on 1 square, with the pan sliced into 16 pieces. It is an estimate only
My grandaughter loved making these so quick and easy . Also fantastic to eat .
Can I ask, how many grams of rice crispies you use? If 1/2 cup of butter is 112 does that mean you use 336 of the crispies? Thanks!
Hi Bryony – the weight of 1 cup will vary depending on the ingredient. 1 cup of Rice Krispies is about 25-30 grams.
My grandgirls love them! And so does their Nana!!
I’m confused is it 12g or 56g of unsalted butter?
Hi Alex,
I’m so sorry! That’s a typo! I’ve updated the recipe now
Can you freeze the squares after
Yup! Just wrap them tightly. I typically recommend letting them thaw in the fridge. Note, that the chocolate topping can discolor if they’re frozen, but it’s still fine to eat. If you want to avoid this, then just skip the chocolate topping before freezing.