What happens when you melt chocolate bars and fold them into Rice Krispies? You get these irresistible, no-bake Mars Bar Squares. Gooey nougat, crunchy cereal, and a milk chocolate topping make them utterly addictive — the perfect sweet treat with a chocolate-caramel punch.
This post was updated July 29, 2025 with new photos and recipe tips. The much-loved recipe remains the same.
Mars Bar Squares are essentially chocolate Rice Krispie treats but made with whole Mars bars and butter instead of marshmallows. The nougat in Mars bars melts down to a luscious, sticky texture that mimics marshmallow, while the caramel and milk chocolate contribute rich flavor. An extra layer of melted milk chocolate on top is optional but highly recommended for a smoother finish and added indulgence.
These no-bake slices are ideal for summer because they require no oven and travel well, making them great for picnics or car snacks. They’re also handy for using up leftover candy after Halloween. In Australia, you might hear them called a Mars bar slice or a Mars bar Rice Bubble slice, since Rice Krispies are sold as Rice Bubbles there.
Making the PERFECT Mars Bar Rice Krispie Treat
To get bars that are nicely gooey but still hold together and slice cleanly, I use the following ratio:
- 1/2 cup unsalted butter (112 grams)
- 4 Mars bars (about 53 grams each), chopped
- 3 cups Rice Krispies / Rice Bubbles (about 90 g)
- 1 cup milk chocolate chips (about 200 g) or 200 g chopped milk chocolate for the topping
If you prefer a softer, gooier texture, reduce the cereal to 2 1/2 cups.
Start by melting the butter in a large saucepan over very low heat. Add the chopped Mars bars and stir gently as they soften and combine with the butter. Keep the heat low to prevent the caramel and chocolate from scorching — patience here makes a smoother mixture.
Pro Tip: If the mixture appears to separate while melting, remove the pan from the heat and whisk vigorously until it becomes smooth and uniform.
Once the chocolate bars and butter are fully melted and combined, turn off the heat and fold in the Rice Krispies. Transfer the mixture into a lightly greased 8×8 inch (20×20 cm) pan and press it down evenly. A 9×9 pan can be used, but the squares will be thinner.
Melt the milk chocolate for the topping and spread it over the pressed cereal mixture. I prefer to let the bars set at room temperature; chilling in the fridge can sometimes cause the chocolate to develop pale spots. When the topping is mostly set (about 80%), score the chocolate lightly with a thin knife where you plan to cut — this reduces cracking as you slice.
Baking Tips & Tricks
- If Mars bars aren’t available, Milky Way bars are a suitable substitute.
- You can use milk, semi-sweet or dark chocolate for the top, depending on how sweet or intense you want the finish.
- When microwaving chocolate for the topping, use medium power and heat in 45-second intervals, stirring between each to prevent burning. Alternatively, melt gently in a double boiler.
- Score the topping with a sharp, thin knife when it’s about 80% set to make clean slices without cracking the chocolate.
- This recipe doubles easily for a 9×13 inch pan if you want more servings.
For other no-bake favorites, consider classic peanut butter Rice Krispie treats, rocky road bars, or a hedgehog slice — all follow a similar easy, no-bake approach and are great for sharing.
Mars Bar Squares
Rate Recipe
Print Recipe
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 / Rice Bubbles (about 90 grams)
- 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 butter to a large saucepan and gently melt over low heat.
-
Stir in the chopped Mars bars and continue stirring as they melt into the butter.
-
Stir continuously until smooth; if the mixture separates remove it from heat and whisk until combined to avoid burning.
-
Turn off the heat and fold in the Rice Krispies (use 2 1/2 cups for gooier bars). Spoon into the prepared pan and press gently to compact the mixture.
-
Melt the chocolate chips in the microwave on medium power in 45-second intervals, stirring between each, until smooth. Alternatively, melt over a double boiler.
-
Spread the melted chocolate over the pressed bars and let sit at room temperature for about 2 hours, or until the topping is set. Score the chocolate when it’s nearly set to make cleaner slices.
Notes
- Rice Krispies: Use 2 1/2 cups for a softer, gooier texture.
- Storage: Keep in an airtight container at room temperature for up to 4 days. Refrigeration or freezing can discolor the chocolate and make the bars too hard; if frozen, thaw in the fridge overnight and then bring to room temperature before serving.
- Nutrition: Nutrition information is an estimate per square when the pan is divided into 16 pieces.
Nutrition
Like this recipe? Rate and comment below!