Mint and Chocolate Fudge Brownie Bars: Easy & Decadent Recipe

Is there a flavor combination more iconic than mint and chocolate? It brings back memories of sneaking after-dinner mints or waiting in line for a scoop of mint chocolate chip ice cream on a hot summer day. If you are a fan of that cool, refreshing zing paired with deep, rich cocoa, you are going to fall in love with these Mint and Chocolate Fudge Brownie Bars.

This recipe is the ultimate “semi-homemade” hack. By elevating a standard box mix with a few gourmet touches—like a marshmallow fluff frosting and crunchy mint biscuits—you create a dessert that looks and tastes like it came from a high-end bakery. Whether you are baking for a holiday cookie swap, a St. Patrick’s Day celebration, or just a Tuesday night craving, these bars deliver maximum impact with minimal effort. Let’s dive into the fudgy, frothy, minty goodness!

Ingredients List

To achieve that perfect balance of chewy brownie and fluffy topping, you will need the following ingredients. We are using a high-quality brownie mix base to save time without sacrificing texture.

this now & bake later ❤️

Timing

This recipe is designed for convenience. While the baking time is short, patience during the cooling phase is key to getting clean slices.

• Prep Time: 15 minutes
• Cook Time: 25-30 minutes
• Cooling Time: 60 minutes
• Total Time: 1 hour 45 minutes (Active effort is minimal!)

Step-by-Step Instructions

Step 1: Preheat and Prep the Pan

Start by preheating your oven to 180°C (350°F), or 160°C if you are using a fan-forced oven. Proper temperature is crucial for that crackly brownie top.

• Action: Grease a 20cm (8-inch) square cake pan lightly with vegetable oil. Line both the base and sides with baking paper (parchment paper), leaving a little overhang on the sides.
• Tip: The paper overhang acts as “handles,” making it incredibly easy to lift the entire brownie slab out of the pan once cooled.

Step 2: Mix the Brownie Batter

Open your brownie box. If you are using a kit that includes a frosting sachet, set that aside for another project—we are making a custom fluff frosting today!

• Action: In a large mixing bowl, combine the brownie mix, melted butter, and the two extra-large eggs.
• Stir: Mix until just blended. Do not overbeat; you want a dense, fudgy texture, not a cakey one.
• Spread: Pour the thick batter into your prepared pan and use a spatula to spread it evenly into the corners.

Step 3: Bake and Cool

Place the pan on the middle rack of your oven.

• Bake: Cook for 25-30 minutes.
• Check: Test for doneness by inserting a round-bladed knife or toothpick into the center. It should come out almost clean—a few moist crumbs are desirable for fudge brownies, but wet batter means it needs more time.
• Cool: Remove from the oven and let the brownie cool completely in the pan. This takes about 1 hour.
• Tip: Do not rush this! If you frost a warm brownie, the topping will melt and slide right off.

Step 4: Create the Mint Marshmallow Frosting

While the brownie cools, prepare the star of the show: the frosting.

• Mix: In a medium bowl, stir together the 150g of vanilla frosting, 50g of marshmallow fluff, and 1/4 teaspoon of peppermint essence. The marshmallow fluff gives it a unique, airy elasticity.
• Color: Add a few drops of green food colouring (or a tiny dab of gel). Mix well until the color is uniform. If you want a punchier mint green, add more color drop by drop.

Step 5: Frost and Decorate

Once the brownie block is cool to the touch, use the baking paper handles to lift it out of the pan and onto a cutting board.

• Swirl: Dollop the green frosting onto the center of the brownie. Using a small palette knife or the back of a spoon, swirl the frosting out to the edges. Make little peaks and waves for visual texture.
• Decorate: Immediately sprinkle the chopped mint cream biscuits over the wet frosting. Press them down slightly so they adhere.
• Serve: Using a sharp knife, cut into 18 bars (3 rows of 6). Wipe the knife between cuts for clean edges.

Nutritional Information

These bars are a rich treat, perfect for portion control (if you have the willpower!). Here is an estimated breakdown per bar:

• Calories: ~210 kcal
• Carbohydrates: 28g (Sugar: 19g)
• Fat: 10g (Saturated: 4g)
• Protein: 2g
• Sodium: 110mg

Note: Nutrition values can vary depending on the specific brand of brownie mix and biscuits used.

Healthier Alternatives

If you love the flavor profile but want to make these Mint and Chocolate Fudge Brownie Bars slightly more wholesome, try these swaps:

• Reduce Fat: Substitute half of the melted butter with unsweetened applesauce. This keeps the brownies moist while significantly cutting down on saturated fat.
• Natural Colouring: Instead of artificial green dye, use a pinch of matcha powder or spirulina. It adds a lovely green hue and a hint of earthiness that pairs well with chocolate.
• Gluten-Free: Simply swap the standard brownie mix for a Gluten-Free Chocolate Brownie Mix and ensure your mint biscuits are gluten-free (or swap them for GF chocolate chips).
• Frosting Swap: For a lighter topping, mix Greek yogurt with a little honey and peppermint extract, though serve immediately as this version won’t hold up at room temperature.

Serving Suggestions

These bars are versatile enough for a party platter or a cozy night in. Here is how to serve them:

• The Café Experience: Serve a bar alongside a hot cappuccino or a peppermint tea to echo the minty notes.
• Dessert Sundae: Warm a brownie bar slightly (before frosting, or frost after warming) and top with a scoop of vanilla bean ice cream and hot fudge sauce.
• Holiday Platter: Cut them into smaller, bite-sized squares and arrange them on a tray with strawberries and candy canes for a festive Christmas dessert.

Common Mistakes to Avoid

Even with a box mix, things can go wrong. Watch out for these pitfalls:

• Overbaking: This is the enemy of the fudge brownie. If your toothpick comes out bone dry, you have baked them too long. Solution: Check them at the 25-minute mark.
• “Toothpaste” Flavor: Peppermint essence is very strong. Adding too much ruins the dessert. Solution: Stick to the 1/4 teaspoon measurement; you can always add more, but you can’t take it out!
• The Messy Cut: Cutting brownies while they are warm or using a dull knife results in squashed bars. Solution: Chill the frosted brownies in the fridge for 20 minutes before slicing for razor-sharp edges.

Storing Tips

These bars store beautifully, making them great for meal prep or gifts.

• Room Temperature: Store in an airtight container in a cool, dry place for 2-3 days.
• Fridge: In hot weather, keep them in the fridge to prevent the marshmallow frosting from getting too soft. They will last up to 5 days.
• Freezer: You can freeze the unfrosted brownie slab for up to 3 months. However, the marshmallow frosting does not thaw well, so it is best to frost them fresh.

Conclusion

There you have it—Mint and Chocolate Fudge Brownie Bars that are as fun to make as they are to eat. This recipe proves that you don’t need to be a professional pastry chef to create a stunning, multi-layered dessert. The combination of dense chocolate brownie, fluffy marshmallow mint frosting, and the crunch of the biscuits is a textural masterpiece.

Try it out this weekend! Did you use Oreos or a different mint biscuit? Let us know in the comments below. We’d love to see your creations! Don’t forget to rate the recipe and subscribe to our blog for more easy baking hacks.

FAQs

Q1. Can I use peppermint extract instead of essence?

Yes, but be careful. Extract is often stronger than essence. If using a high-quality peppermint extract (oil-based), start with 1/8 of a teaspoon and taste the frosting before adding more.

Q2. Can I make the brownies from scratch?

Absolutely. If you prefer homemade over box mix, feel free to use your favorite fudge brownie recipe as the base. Just ensure it fits a 20cm square pan so the thickness remains correct for the baking time.

Q3. The frosting is too runny. What do I do?

If your kitchen is warm, the frosting might loosen. Place the bowl in the fridge for 10-15 minutes to firm up before swirling it onto the brownie. Adding a tablespoon of powdered sugar can also help stiffen it up.

Q4. Can I use a different flavor?

Definitley! This base recipe is very adaptable. You could use orange extract and orange food coloring for a “Jaffa” style brownie, or strawberry essence and pink coloring for a berry twist.

Mint and Chocolate Fudge Brownie Bars

Evelyn Marcella Rivera

All the iconic mint–chocolate nostalgia in an easy, semi‑homemade bar. Start with a fudgy brownie mix, then finish with a fluffy mint marshmallow frosting and crunchy mint biscuit pieces for a bakery‑worthy treat in under two hours.

Print Recipe Pin Recipe

Prep Time 15 minutes mins

Cook Time 30 minutes mins

Cooling Time 1 hour hr

Total Time 1 hour hr 45 minutes mins

Course Dessert

Cuisine American

Servings 18 bars

Calories 210 kcal

Equipment

• 8-inch square cake pan
• Parchment Paper
• Mixing Bowls
• Spatula
• Hand mixer (optional)
• Measuring cups and spoons
• Knife

Ingredients

  

Brownie Base

• 1 box brownie mix Betty Crocker™ Frosted or Triple Chocolate Fudge
• 125 g butter melted
• 2 extra large eggs room temperature
• vegetable oil for greasing pan

Mint Marshmallow Frosting & Topping

• 150 g vanilla frosting tub frosting such as Betty Crocker™ Creamy Deluxe™
• 50 g marshmallow fluff
• 1/4 tsp peppermint essence be precise; it’s potent
• green food colouring drops or gel
• 8 mint cream biscuits roughly chopped (e.g., Oreos or Mint Slices)

Instructions

 

• Preheat & prep: Heat oven to 350°F (180°C) or 320°F (160°C) fan. Lightly grease a 20cm/8-inch square pan with vegetable oil and line base and sides with parchment, leaving overhang for easy lifting.
• Make batter: In a large bowl, combine brownie mix, melted butter, and 2 extra-large eggs. Stir just until combined (do not overbeat). Spread into the prepared pan.
• Bake: Bake 25–30 minutes until a toothpick inserted near the center comes out with a few moist crumbs. Cool completely in the pan, about 60 minutes.
• Mint fluff frosting: In a medium bowl, stir together vanilla frosting, marshmallow fluff, and peppermint essence. Tint with a few drops of green food colouring until evenly pale mint.
• Frost & finish: Lift cooled brownie slab onto a board. Spread frosting to edges in swoops, then scatter chopped mint cream biscuits on top and press lightly to adhere.
• Slice & serve: Cut into 18 bars (3×6). Wipe the knife between cuts for clean edges.

Notes

For extra minty crunch, chill frosted slab 20–30 minutes before slicing. Store airtight at room temp up to 2 days or refrigerate up to 4 days.

Keyword brownie bars, marshmallow fluff frosting, mint chocolate, semi-homemade, St. Patrick’s Day