If you're looking for a colourful, chewy bake that's guaranteed to disappear fast, these M&M cookie bars are the answer. This easy traybake has everything you love about cookies - soft centres, golden brown edges and pools of melted chocolate - all baked into one simple, sliceable M&M slice. Packed with bright M&M's and chocolate chunks, it's a fun and fuss-free treat that's perfect for sharing.
Save this recipe for later?
Enter your email and I’ll send it your way!
A Quick Look At The Recipe
✅ Recipe Name: M&M Cookie Bar Recipe
🕒 Ready In: 40 minutes
👪 Serves: 12
🍽 Calories: 431
🥣 Main Ingredients: Butter, Sugar, Eggs, Plain Flour, M&Ms, Chocolate
📖 Dietary Info: Vegetarian, freezer-friendly
👌 Difficulty: Easy
Summarise & Save This Content On
I still remember the first time I made this M&M chocolate slice. The delicious scent of warm sugar and vanilla filled the kitchen as it baked, and as soon as I lifted it from the tin, everyone gathered around waiting for a taste.
That first chewy square, still slightly warm from the oven, was enough to make this a regular bake in our house whenever we fancy something sweet and comforting.
If you love cookie bar recipes you'll also like my mini egg cookie bars and chocolate orange cookie bars.
Just made the batter and it is in the oven and looks amazing! Can't wait to taste it! Thanks so much for this awesome recipe!!!
- Sarih
Jump to:
✔️ Why you'll love this M&M cookie bars recipe
- Soft, chewy texture with golden brown edges - just like the perfect cookie, but in an easy slice.
- Packed with colour and chocolate from M&M's and choc chunks.
- No fiddly shaping or rolling - simply press the dough into a tin lined with parchment paper and bake.
- Perfect for sharing as a fun M&M slice for parties, lunchboxes, bake sales or weekend treats.
- Quick and simple to make with basic store cupboard ingredients.
- Easy to customise with your favourite mix-ins or extra chocolate.
- Stores and freezes beautifully, so you can always have a chewy M&M chocolate slice ready to enjoy.
🥘 Ingredients
A full ingredients list along with Metric and US Customary measurements, can be found in the recipe card at the end of this post.
M&M's - we used a mixture of chocolate M&M's and crispy M&M's for extra texture and colour. You can use any variety you like.
M&M's Chocolate Bar - broken into small chunks for pockets of melted chocolate. Alternatively, use chocolate chips if that's what you have.
Butter - unsalted butter is best. Melt the butter before using so it blends smoothly into the mixture.
Sugar - a mixture of golden caster sugar (granulated sugar) and light brown sugar gives the perfect chewy texture. You can use all light brown sugar for an even fudgier, richer result.
Eggs - use 2 large free-range eggs at room temperature.
Vanilla Extract - use a good quality vanilla extract, not vanilla essence, for the best flavour.
Plain flour (all-purpose flour) - for the base of the recipe.
Need to substitute an ingredient?
Have an allergy or dietary preference? Let AI customise the recipe for you.
📖 Variations
- Swap the sweets - try different candy combinations such as Smarties, chopped Mars bars, or even Mini Eggs for a fun Easter-themed M&M slice.
- Make them extra fudgy - replace the golden caster sugar and light brown sugar with the same quantity of dark brown sugar for a deeper flavour and richer, chewier texture.
- Change the chocolate - use peanut butter chips instead of the chocolate chunks for a sweet and salty twist.
- Add crunch - stir through a handful of chopped unsalted nuts, such as walnuts or pecans, for extra texture.
- White chocolate lovers - increase the white chocolate chips and reduce the M&M's slightly for a creamier flavour profile.
🔪 Instructions
The recipe card with ingredient quantities and detailed instructions can be found at the bottom of the post
Prep: Preheat the oven to 180°C (160°C fan / 350°F / Gas Mark 4) and line a 20cm (8") square baking tin or small brownie tin with parchment paper, leaving an overhang for easy removal.
One: Cream together the melted butter and sugars until pale, smooth and slightly fluffy.
Two: Beat in the eggs and vanilla extract until fully combined.
Three: Stir in the plain flour and salt until a soft cookie dough forms with no streaks of flour remaining.
Four: Make sure the mixture is thoroughly combined at this stage so the texture is even.
Five: Fold in the M&M's and chocolate chunks (or chocolate chips).
Six: Spoon the mixture into the lined tin and smooth the top with the back of a spoon or spatula.
Seven: Bake in the oven for 30 minutes, or until the edges are golden brown and the centre is just set for a chewy texture.
Eight: Remove from the oven and gently press a few extra M&M's into the top while still warm. Allow the M&M cookie bars to cool completely in the tin before lifting out and slicing into bars.
Top Tips
- Line your tin with parchment paper and leave an overhang to lift the slice out easily.
- Don't overbake if you want soft, chewy M&M cookie bars.
- Press extra M&M's into the top after baking to stop the colours running.
- Sprinkle a tiny pinch of salt on top to balance the sweetness.
- Chill the tin in the fridge or freezer for 30-60 minutes to speed up cooling.
- Let the slice cool completely before cutting for neat edges.
- Lift out using the parchment paper and cut on a flat board.
- Use a long, sharp knife and wipe it clean between each cut.
🍴 Serving suggestions
These cookie bars are great as a treat with a glass of ice cold milk. They also double up as an easy dessert or pudding, served warm with honeycomb ice cream and drizzled with chocolate fudge sauce!
Storage
Store - keep the M&M cookie bars in an airtight container at room temperature for up to 3 days.
Refrigerate - they can be stored in the fridge for up to a week if you prefer a firmer texture.
Freeze - wrap individual bars or the whole slice in parchment paper and place in a freezer-safe container or bag for up to 3 months. Defrost at room temperature before serving.
❓ Frequently asked questions
Yes! You can use chocolate chips, chopped chocolate bars, Smarties, or even Mini Eggs for a themed variation.
Use all light or dark brown sugar instead of mixing with caster sugar, and avoid overbaking.
Make sure the slice is completely cooled, lift it out using the parchment paper, and use a long sharp knife, wiping it clean between cuts.
Troubleshooting Guide
| Problem | Fix |
|---|---|
| Bars are too soft or gooey in the centre | You may have underbaked slightly. Bake until edges are golden brown and the centre is just set. Let bars cool completely before slicing. |
| M&M colours bleed into the dough | Press extra M&M's into the top after baking rather than mixing them all in, or use crispy M&M's for less colour running. |
| Bars are too sweet | Reduce the sugar slightly or add a pinch of salt to balance the sweetness. |
😋Related recipes
More bars and brownies to try!
Tried it? Let me know what you think and rate it ⭐️ below. Tag me @effortlessf00d-I'd love to see! Don't forget to subscribe for more recipes.
Recipe
M&M Cookie Bars Recipe
Save this recipe for later?
Enter your email and I'll send it your way!
Ingredients
- 200 g Butter melted
- 125 g Golden Caster Sugar or use white caster sugar
- 125 g Light Brown Sugar
- 2 Eggs
- 2 teaspoon Vanilla Extract
- 275 g Plain Flour (all-purpose flour)
- 150 g M&M Chocolate Bar cut into chunks (or use chocolate chips instead)
- 150 g M&M's chocolate ones (or your preference)
Topping
- 50 g M&M's I used crispy M&M's but any flavour is fine.
Instructions
- Preheat the oven to 180°C (160°C fan / 350°F / Gas Mark 4) and line a 20cm (8") square baking tin or small brownie tin with parchment paper, leaving an overhang for easy removal.
- Cream together the melted butter and sugars in a large mixing bowl until pale and fluffy.200 g Butter, 125 g Golden Caster Sugar, 125 g Light Brown Sugar
- Beat in the eggs and vanilla extract until fully combined.2 Eggs, 2 teaspoon Vanilla Extract
- Stir in the plain flour until a soft cookie dough forms with no streaks of flour remaining.275 g Plain Flour (all-purpose flour)
- Fold in the M&M's and chocolate chunks (or chocolate chips).150 g M&M Chocolate Bar, 150 g M&M's
- Spoon the mixture into the lined tin and smooth the top with the back of a spoon or spatula.
- Bake in the oven for 30 minutes, or until the edges are golden brown and the centre is just set for a chewy texture. Remove from the oven and gently press a few extra M&M's into the top while still warm. Allow the M&M cookie bars to cool completely in the tin before lifting out and slicing into bars.50 g M&M's
Notes
- Sugar options: A mix of golden caster sugar and light brown sugar gives chewy bars. Use all brown sugar for extra fudgy bars.
- Chocolate: Use chocolate chunks, chips, or M&M chocolate bars. Mix M&M's for colour and crunch.
- Chewy bars: Don't overbake. Edges should be golden brown and the centre just set.
- Extra M&M's: Press a few on top after baking to prevent colours running.
- Cooling: Let bars cool completely before slicing. Chilling in the fridge or freezer for 30-60 minutes speeds this up.
Paula says
I just made this one with a chocolate orange - just a whole one smashed up.
Dannii says
Anything with m&ms is good with me. These cookie bars look amazing.
Sarih says
Just made the batter and it is in the oven and looks amazing! Can't wait to taste it! Thanks so much for this awesome recipe!!!
Beth says
This looks amazing and so delicious! Can't wait to give this a try! My family is going to love this!
Shashi at SavorySpin says
These look so good - perfect to start the week off with!
SHANIKA says
OMG! I'm loving these M&M Cookie bars! They are such an easy sweet treat for the entire family!
Mirlene says
These cookie bars are absolutely amazing! Delicious and just the way I like mine. Yum!
Michelle Boule says
I made these and shared with my family and we all loved them! Such an easy recipe to make too!
Maria says
This recipe is so versatile I can easily swap the candies with whatever I'm craving!
Helen says
These look SO good! Makes me wonder why I ever bother rolling dough into cookies! 🙂
Adrianne says
The melted chocolate in these cookie bars looks simply irresistible! The ingredients sound simple also, what a great recipe, thanks for sharing.
Bintu | Budget Delicious says
I just know my kids would adore these - and they would definitely find it hard to wait for them to cool! They look so tasty, I can't wait to give them a try.