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Mars Bar Slice (Mars Rice Krispie Treats) Recipe

Published: Jul 27, 2026 by Eliza · This post may contain affiliate links · Leave a Comment

Jump to Recipe· 3.9 from 6 reviews

If you’re on the hunt for an indulgent yet surprisingly simple treat that will wow anyone with a sweet tooth, the Mars Bar Slice (Mars Rice Krispie Treats) Recipe is your new best friend. This luscious slice combines the ooey-gooey richness of melted Mars bars with the irresistible crunch of Rice Krispies, all topped with a silky chocolate layer that sets it apart from your average bars. It’s dessert nostalgia reinvented—perfect for sharing with family, gifting to friends, or simply treating yourself to a moment of pure bliss.

Ingredients You'll Need

A close-up view of a shiny silver pot filled with smooth, glossy dark brown chocolate sauce that looks thick and creamy. Inside the pot is a gray silicone spatula partially covered in the rich chocolate, with the spatula's flat end dipped in the sauce, lifting some chocolate slightly above the surface. The pot sits on a white marbled surface, and small bubbles and streaks of chocolate line the inside walls of the pot, showing the sauce's silky texture. Photo taken with an iphone --ar 4:5 --v 7

This Mars Bar Slice (Mars Rice Krispie Treats) Recipe uses straightforward, pantry-friendly ingredients that come together to create a stunningly delicious dessert. Each component plays a vital role: the Mars bars provide a caramel-chocolate melt, the Rice Krispies add that perfect crispy bite, and the chocolate topping seals the deal with smooth, glossy goodness.

  • Mars bars (260 g / 5 bars): The star of the show; provides caramel and nougat richness that becomes beautifully melty.
  • Butter (115 g / ½ cup): Enhances creaminess and helps everything stick together smoothly.
  • Sea salt (¼ tsp): Adds balance by cutting through the sweetness; only necessary if using unsalted butter.
  • Rice Krispies (110 g / 3 ½ cups): Offers that signature crispy crunch and airy texture.
  • Semisweet chocolate (300 g): Creates a rich, slightly bittersweet chocolate layer that contrasts beautifully with the sweet base.
  • Coconut oil (15 g / about 2 tbsp): Gives the chocolate topping a glossy, smooth finish and holds the texture perfectly.

How to Make Mars Bar Slice (Mars Rice Krispie Treats) Recipe

Step 1: Preparing the Mars Bar Rice Krispie Base

Start by lining an 8 or 9-inch square pan with parchment paper to ensure an easy release later. Cut the Mars bars into manageable 1 to 2-inch pieces and place them in a large saucepan along with the butter and salt if you are using unsalted butter. Gently melt this mixture over medium heat, stirring frequently to avoid burning. Once completely smooth, immediately stir in the Rice Krispies so they’re fully coated with the luscious Mars bar syrup. Transfer this sticky mixture quickly to your lined pan and press it down evenly with a spatula to create a uniform, crispy base.

Step 2: Melting the Chocolate Topping

While the base sets, it’s time to prepare the decadent chocolate topping. Combine the semisweet chocolate chips or chunks, the coconut oil, and a pinch of sea salt in a microwave-safe bowl. Heat in short bursts of 20 to 30 seconds, stirring in between, so the chocolate melts gradually without overheating. Once about 80% melted, stir until smooth and glossy. This method ensures a velvety texture that will beautifully coat the Mars bar layer.

Step 3: Assembling and Setting the Slice

Pour the silky chocolate over the prepared Rice Krispie base, gently spreading it evenly with an offset spatula or the back of a spoon. Let the slice cool at room temperature or pop it in the fridge to speed up the setting process. Once firm, remove the slice from the pan using the parchment paper. For cleaner cuts, let the slice soften slightly at room temperature before slicing into your desired portions — 16 pieces about 2 x 2 inches is a great starting point.

How to Serve Mars Bar Slice (Mars Rice Krispie Treats) Recipe

The image shows several square chocolate treats placed closely together on a white marbled surface. Each square has two layers: a thick, smooth dark chocolate layer on top and a bottom layer made of crispy, light brown cereal mixed with chocolate or caramel, creating a textured look with small holes. One square is slightly tilted, showing the side view clearly with its two distinct layers. The chocolate top layer appears shiny and solid, while the bottom layer looks crunchy and airy. photo taken with an iphone --ar 4:5 --v 7

Garnishes

Elevate your Mars Bar Slice by sprinkling some flaky sea salt on top just before serving to heighten the chocolate and caramel flavors. You can also add chopped toasted nuts for an extra crunch, or even a drizzle of caramel sauce to double down on that luscious, gooey element.

Side Dishes

This treat pairs wonderfully with a scoop of vanilla bean ice cream or a dollop of freshly whipped cream, balancing the richness of the slice with creamy, cool textures. A fresh cup of coffee or a creamy hot chocolate also makes the perfect beverage companion.

Creative Ways to Present

For a fun twist, cut your Mars Bar Slice into bite-sized squares and serve on a decorative platter with mini cupcake liners, perfect for sharing at parties. Alternatively, layer pieces in a dessert trifle with whipped cream and berries for an elevated, crowd-pleasing dessert experience.

Make Ahead and Storage

Storing Leftovers

Keep your Mars Bar Slice fresh by storing it in an airtight container lined with parchment or wax paper between layers to prevent sticking. It will keep beautifully in the refrigerator for up to two weeks, maintaining its perfect chewy and crunchy texture.

Freezing

If you want to prepare this treat well in advance, freezing is your best friend. Wrap the slice tightly and store it in the freezer for up to six months. When ready, thaw in the fridge or at room temperature for the best texture and flavor.

Reheating

These slices are best enjoyed at room temperature, but if you prefer them a little warm, gently microwave a piece for 10 to 15 seconds. Be careful not to overheat, or the chocolate may lose its silky shine and the Rice Krispies might become too soft.

FAQs

Can I use other cereal instead of Rice Krispies?

You can substitute with similar puffed rice cereals, but Rice Krispies are ideal for that classic crunch and texture. Using flakes or granola may alter the final crispiness and binding.

Is it necessary to use coconut oil in the chocolate layer?

Coconut oil helps give the chocolate topping a smooth, shiny finish and a slightly softer set. Without it, the chocolate may harden too firmly and be more prone to cracking.

Can I make this slice dairy-free?

Yes! Use dairy-free Mars bar alternatives, dairy-free butter, and dairy-free chocolate. Be sure to check labels to keep the treat just as delectable without dairy.

How long does it take for the Mars Bar Slice to set?

At room temperature, it usually takes about 1 to 2 hours to fully set. Refrigeration can speed this up significantly to around 30 to 45 minutes.

Why does the Mars Bar mixture sometimes stick to the pan?

Using parchment paper is key to preventing sticking. Additionally, pressing the mixture firmly and evenly before it fully cools ensures a more cohesive slice that releases easily.

Final Thoughts

This Mars Bar Slice (Mars Rice Krispie Treats) Recipe is a delightful and scrumptious dessert that brings together nostalgic flavors with a satisfying crunch and a luxuriously smooth chocolate finish. It’s as much fun to make as it is to eat and is sure to become a beloved staple in your dessert repertoire. So go ahead, whip up a batch, and watch your family and friends fall in love one delicious bite at a time!

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Mars Bar Slice (Mars Rice Krispie Treats) Recipe

Mars Bar Slice (Mars Rice Krispie Treats) Recipe


5 Stars 4 Stars 3 Stars 2 Stars 1 Star

3.9 from 6 reviews

  • Author: Eliza
  • Total Time: 2 hours 35 minutes (including chilling time)
  • Yield: 16 servings
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Description

This Mars Bar Slice recipe transforms the beloved Mars bars into a decadent layered treat featuring a gooey Mars bar and rice krispie base topped with a smooth chocolate layer. Easy to prepare and perfect for sharing, these slices combine gooey caramel, crispy cereal, melty chocolate, and a hint of salt for the ultimate indulgence.


Ingredients

Mars Bar Rice Krispie Layer

  • 260 g Mars bars (5 x 52 g bars), cut into 1-2 inch pieces
  • 115 g butter (½ cup / 1 stick, salted or unsalted)
  • ¼ tsp sea salt (only if using unsalted butter)
  • 110 g rice krispies (3 ½ cups)

Chocolate Topping

  • 300 g semisweet chocolate
  • 15 g coconut oil (about 2 tbsp)
  • ¼ tsp sea salt


Instructions

  1. Prepare Pan: Line an 8 or 9 inch square baking pan with parchment paper for easy removal of the slice later.
  2. Melt Mars Bars Mixture: Place the chopped Mars bars, butter, and salt (only if unsalted butter) into a large saucepan. Heat over medium heat while stirring continuously until everything melts and the mixture becomes smooth. Be careful not to burn the bottom.
  3. Add Rice Krispies: Once the mixture is smooth and melted, turn off the heat and quickly add the rice krispies. Stir well until all cereal pieces are evenly coated.
  4. Press into Pan: Scrape the sticky mixture into the prepared pan. Use a spatula to press and spread it evenly into a flat layer. Set aside while preparing the chocolate topping.
  5. Melt Chocolate Topping: Add semisweet chocolate, coconut oil, and sea salt to a microwave-safe bowl. Heat in short bursts of 20-30 seconds, stirring between each, until the chocolate is about 80% melted. Stir continuously until fully melted and smooth.
  6. Assemble and Chill: Pour the melted chocolate over the rice krispie layer. Spread evenly using an offset spatula. Allow to set at room temperature or place in the fridge to chill faster until firm.
  7. Cut and Serve: Once set, remove from the pan using the parchment paper. If too cold, let sit at room temperature briefly to soften for easier cutting. Slice into 16 pieces or preferred size using a sharp knife.
  8. Storage: Store slices in an airtight container with parchment or wax paper between layers to prevent sticking. Keep refrigerated for up to 2 weeks or freeze for up to 6 months. Bring to room temperature before serving for best texture and flavor.

Notes

  • Use salted butter to skip adding extra sea salt or use unsalted butter and include salt for better control.
  • Be careful not to overheat the chocolate topping to avoid burning or seizing.
  • Press the rice krispie mixture firmly into the pan for even cutting and better layering.
  • Allow slices to soften slightly at room temperature after refrigeration for easier cutting and optimum chewiness.
  • Parchment paper lining helps with easy removal and cleanup.
  • Substitute semisweet chocolate with milk or dark chocolate based on preference.
  • Prep Time: 25 minutes
  • Cook Time: 15 minutes
  • Category: Dessert
  • Method: Stovetop
  • Cuisine: Western

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Hi there! I’m Eliza, I’m a passionate home cook, recipe creator, and storyteller who believes that food is a universal language that connects us all. I live with my little boy, Ely, and together we fill our kitchen with laughter, love, and the comforting aroma of something delicious made with care.

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