When you melt chocolate bars and fold them into Rice Krispies, you get irresistible no-bake Mars Bar Squares. Gooey nougat, caramel and crunchy cereal combine under a milk chocolate topping for a sweet, addictive treat.
This post was updated July 29, 2025 with fresh photos and extra tips. The beloved recipe remains the same.
Mars Bar Squares are a twist on classic chocolate Rice Krispie treats: instead of melting marshmallows, butter and chocolate, this version uses four Mars bars plus butter. The nougat melts into a soft, chewy layer while the caramel and milk chocolate create a rich, satisfying flavor. An extra layer of melted milk chocolate on top is optional but delicious.
These no-bake bars are ideal for summer, road trips, or anytime you want a quick treat. They’re also great for using up leftover Halloween candy. In Australia you might see them called a Mars bar slice or a Mars bar Rice Bubble slice—Rice Krispies are known as Rice Bubbles there.
Making the PERFECT Mars Bar Rice Krispie Treat
To get a nicely balanced texture—gooey but still sliceable—I use the following ingredient ratios:
- 1/2 cup unsalted butter (112 grams)
- 4 Mars bars (about 53 grams each), chopped
- 3 cups Rice Krispies / Rice Bubbles (about 90 grams)
- 1 cup milk chocolate chips, or about 200 g chopped milk chocolate for the topping
If you prefer a softer, chewier bar, reduce the cereal to 2 1/2 cups.
Begin by melting the butter over very low heat in a large saucepan. Add the chopped Mars bars and stir gently as they melt into the butter. Keep the heat low to prevent the caramel and chocolate from burning.
Pro tip: If the butter and melted Mars bars begin to separate, take the pan off the heat and whisk vigorously until smooth.
Once everything is fully melted and smooth, stir in the Rice Krispies until they are evenly coated. Press the mixture into a lightly greased 8×8 inch (20×20 cm) pan—using a 9×9 pan will work but yields thinner squares.
Top the pressed mixture with melted milk chocolate. I prefer allowing the chocolate to set at room temperature; chilling can cause the surface to develop white streaks or bloom. When the topping is mostly set—about 80%—lightly score the chocolate where you plan to slice. This helps prevent cracking when cutting.
Baking Tips & Tricks
- If Mars bars aren’t available, Milky Way bars are a fine substitute.
- Choose milk, semi-sweet or dark chocolate for the topping depending on your sweetness preference.
- Melt topping chocolate in the microwave at medium power in 45-second bursts, stirring between intervals to avoid scorching. Alternatively, use a double boiler over low heat—make sure the water doesn’t touch the bowl holding the chocolate.
- Score the chocolate topping with a thin, sharp knife when it’s about 80% set to make cleaner slices and prevent cracking.
- You can double this recipe and bake it in a 9×13 inch pan for more servings.
For more no-bake bars and slices, try other Rice Krispie or rocky road-style recipes to vary flavors and textures.
Mars Bar Squares
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Equipment
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8×8 inch (20×20 cm) pan
Ingredients
- 1/2 cup unsalted butter (112 grams)
- 4 Mars bars (about 53 g each), chopped
- 3 cups Rice Krispies (about 90 g), aka Rice Bubbles
- 1 cup milk chocolate chips (about 200 g) or chopped milk chocolate
Instructions
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Lightly grease an 8×8 inch (20×20 cm) square pan.
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Add the butter to a large saucepan and melt gently over low heat.
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Stir in the chopped Mars bars and continue stirring as they melt into the butter.
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Keep stirring until the mixture is smooth. If it starts to separate, remove from heat and whisk until combined. Stir constantly to avoid burning.
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Turn off the heat and fold in the Rice Krispies. Use 2 1/2 cups for gooier bars if desired.
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Press the mixture into the prepared pan, smoothing the top with a greased spatula or lightly oiled hands.
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Melt the chocolate chips in a heatproof bowl in 45-second microwave intervals on medium power, stirring between each interval, or melt over a double boiler. Stir until smooth and spread over the pressed bars.
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Let the bars sit at room temperature for about 2 hours, or until the chocolate topping is set. When the topping is mostly set, score the surface with a thin knife where you plan to slice to avoid cracking, then cut into 16 squares.
Notes
- Rice Krispies: Use 2 1/2 cups for a softer, chewier bar.
- Storage: Store squares in an airtight container at room temperature for up to 4 days. Refrigeration can cause chocolate bloom and make the bars too firm. If frozen, thaw in the fridge overnight and bring to room temperature before serving.
- Nutrition: Nutrition information is an estimate per square when the pan is cut into 16 pieces.
Nutrition
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