Imagine walking into your kitchen, the smell of melted chocolate and buttery goodness filling the air and knowing you’re about to make the happiest holiday dessert ever, that’s exactly what happens when you bake these M&M Cookie Bars. These aren’t your ordinary cookie bars; they’re soft, chewy, and packed with colorful M&Ms that make each bite feel like a little celebration.
There are a lot of cookie bar recipes, but there’s something magical about this one, it’s simple, stress-free, and yet, every square screams festive cheer. If you’ve ever wanted Christmas cookie bars that are as fun to make as they are to eat, grab your mixing bowl, and let’s turn these humble ingredients into the kind of treat everyone keeps sneaking from the pan.
Trust me, by the time you’re done, you’ll feel like a holiday baking hero, and your friends and family won’t stop asking for the recipe.
What Makes These M&M Cookie Bars So Good
No stress, all reward – unlike complicated holiday desserts, this recipe is simple, forgiving, and perfect for bakers of all levels.
Perfect for every occasion – snack, party treat, or last-minute gift, these bars fit the bill every time.
Fun to make (and even more fun to eat!) – fold in colorful M&Ms, sneak a few as you go, and enjoy the little victories of your holiday baking adventure.
Flexible and personalizable – swap in your favorite mix-ins, sprinkle on extra chocolate, or add a peppermint twist, it’s your playground, and these bars are your canvas.
Bakes fast, disappears faster – in less than an hour, you’ll have a pan full of joy, and everyone will be sneaking bites before dinner.
What You’ll Need for M&M Cookie Bars
- Salted Butter: I recommend using real butter for that rich, chewy texture, it really makes the bars taste buttery and soft.
- Light Brown Sugar: It’s best if you pack it slightly for that warm, caramel-like flavor that keeps every bite cozy.
- Granulated Sugar: Always add a bit to help the edges get lightly crisp while keeping the centers chewy.
- Large Egg + Egg Yolk: I recommend this combo because it binds everything together while giving your bars a tender, fudgy texture.
- Vanilla Extract: It boosts all the flavors and adds that cozy, homemade aroma.
- All-Purpose Flour: Always spoon and level your flour for accurate texture, it gives the bars structure without making them dense.
- Baking Soda: I recommend using just enough to lift the bars slightly, so they’re soft and chewy but not flat.
- Extra Pinch of Salt: It makes the chocolate and sweetness pop perfectly.
- Dark Chocolate Chips: Always go for quality chocolate, these melt into gooey pockets that everyone will love.
- M&M’s: For fun and festive bites, they make each square feel joyful and holiday-ready.
Want to double the holiday magic? Pair these cookie bars with my peppermint brownies, your taste buds will thank you!
How to Make M&M Cookie Bars
Step 1: Get your kitchen ready
Start by preheating your oven to 325°F, this temperature keeps the bars soft and chewy without over-browning. Line a 9×13-inch pan with parchment paper, or lightly grease it if you prefer. Tip: leave a little overhang of parchment on the sides, it makes lifting the whole batch out later a piece of cake.
Step 2: Mix the buttery base
In a large bowl, combine your melted salted butter with both the brown and granulated sugars. I like to whisk until it’s smooth and a little glossy, it’s like a tiny preview of how good these bars are going to taste. Then add the egg and extra yolk, followed by the vanilla extract. Tip: if your butter is still slightly warm, don’t worry, it helps melt the sugars slightly, giving a fudgy texture.
Step 3: Fold in the dry stuff carefully
Add the flour, baking soda, and that pinch of salt (If you want, since we’re already using salted butter). Use a spatula and fold gently until just combined. You want the dough soft, tender, and ready to hug those chocolate chips and M&Ms.
Step 4: Add the chocolate and M&M magic
Fold in the dark chocolate chips and most of the M&M’s, leaving a few aside for topping. Tiny trick: press a few of the reserved M&M’s gently on top of the spread dough, it makes the bars look like they were sprinkled with little holiday treasures.
Step 5: Spread the love
Spoon your dough into the prepared pan and spread it evenly. I like to use an offset spatula or the back of a spoon to get it nice and smooth. Don’t squish too hard, you still want those bars to have a soft, thick center.
Step 6: Bake with love
Pop it in the oven for 22–24 minutes. Tip: the edges should look lightly golden, but the center will still be soft, it will set as it cools. If you like extra fudgy centers, pull them out closer to 20 minutes.
Step 7: Cool (and sneak a taste!)
Let the bars cool in the pan for about 10 minutes before cutting. Run a knife around the edges before lifting out the whole batch, it keeps the squares neat and perfect for sharing. And yes, it’s perfectly fine to sneak a warm bite while they’re cooling.
If your kitchen is already smelling like Christmas with these bars, add a little extra magic with my gingerbread cookies, they’re soft, spicy, and perfect for dipping in cocoa!
Common Issues and How to Fix Them
Bars too flat or spreading too much: It’s usually the butter being too warm or overmixing the dough. Tip: chill your dough for 10–15 minutes before spreading it in the pan, it helps them hold their shape.
Edges too crisp, center undercooked: Oven temps vary! I recommend checking your bars a few minutes early. If the center still looks soft but the edges are golden, they’ll finish setting as they cool.
Bars too dry: Overbaking is the culprit. Always start checking at 20 minutes, and remember they’ll look slightly underbaked in the middle, that’s perfect for soft, chewy bars.
Bars sticking to the pan: Parchment paper is your best friend! Always line your pan with it and leave an overhang, no sticky fingers, no stress.
What to Serve With M&M Cookie Bars
- A cozy mug of hot cocoa – extra chocolatey, marshmallows optional but highly recommended.
- Vanilla or peppermint ice cream – melt a warm square on top and watch the magic happen.
- Coffee or latte – the perfect pick-me-up pairing for a sweet snack break.
- Fresh fruit – sliced strawberries or oranges balance the sweetness and add a festive touch.
- Whipped cream or frosting drizzle – simple, indulgent, and makes every bite feel extra special.
- Holiday cookie platter – mix with peppermint cookies or other treats for a fun, colorful spread.
- Airtight container at room temperature – keeps bars soft and chewy for up to 4 days. Tip: separate layers with parchment paper so M&Ms don’t stick or get squished.
Tips for Keeping Your Cookie Bars Perfect
Refrigerate for longer freshness – store in an airtight container and enjoy within a week. Perfect if you like a slightly firmer, chilled bite.
Freeze for later – wrap individual squares in plastic wrap and place them in a freezer-safe bag. Thaw at room temp or warm for a few seconds in the microwave for fresh-from-the-oven vibes.
Enhance flavor on storage – tip: after a day or two, a few seconds in the microwave bring the chocolate and M&Ms back to that soft, melty, irresistible state.
Perfectly Soft M&M Cookie Bars
Ingredients
- 2 ⅓ cups all-purpose flour spooned and leveled
- ½ teaspoon baking soda
- Extra pinch of salt optional
- 1 cup salted butter melted and slightly cooled
- 1 large egg + 1 extra yolk
- 1 cup light brown sugar packed
- ⅓ cup granulated sugar
- 1 ½ teaspoons vanilla extract
- 1 ¼ cup dark chocolate chips
- 1 ⅓ cups M&M’s
Instructions
- Preheat your oven to 325°F so your bars bake soft and chewy without over-browning. Line a 9×13-inch pan with parchment paper or lightly grease it if you prefer. I always leave a little overhang on the sides, it makes lifting the entire batch out so much easier later.
- In a large bowl, whisk together the melted salted butter with the brown and granulated sugars until the mixture looks smooth and a little glossy.
- Add the egg and extra yolk, then pour in the vanilla extract, whisking until everything is well combined. If your butter is still just a bit warm, that’s actually a bonus, it helps melt the sugars slightly, giving the bars a tender, fudgy texture.
- Add the flour, baking soda, and a pinch of salt to the bowl. Lightly incorporate everything with a spatula, mixing only until the batter looks unified. You want the dough soft and tender.
- Next, fold in the dark chocolate chips and most of the M&M’s, leaving a few aside to sprinkle on top. Press a few of the reserved M&M’s gently into the top of the dough, it adds a festive, colorful touch that makes the bars look extra special.
- Spoon the dough into your prepared pan and spread it evenly. I like to use an offset spatula or the back of a spoon to smooth it out, but don’t press too hard, the bars should stay thick and soft in the center.
- Bake for 22–25 minutes. The edges should be lightly golden, while the center stays soft, it will firm up as it cools. If you prefer extra fudgy bars, check around 20 minutes and remove them once the edges are set.
- Let the bars cool in the pan for about 10 minutes before cutting. Run a knife around the edges first to help lift the whole batch out neatly. Enjoy!
Notes
- You can swap the dark chocolate chips for milk or white chocolate if you want a different flavor twist.
- For an extra festive touch, sprinkle a tiny pinch of sea salt on top before baking, it makes the chocolate and M&Ms pop.
- Try adding a teaspoon of cinnamon or pumpkin spice to give the bars a subtle holiday flavor boost.
