If you’re on the hunt for a treat that’s equal parts nostalgic, festive, and crowd-pleasing, look no further than these M&M Cookie Bars. Packed with gooey chocolate chips and studded with those bright candy-coated M&Ms, this recipe comes together in a flash and bakes up into the softest, chewiest bars imaginable. Whether you’re making them for a birthday bash, holiday celebration, or just because it’s Tuesday, these bars guarantee big flavor and big smiles in every buttery bite.

Ingredients You’ll Need

These simple ingredients are baking pantry staples, but each one plays a leading role in building the irresistible taste and texture that make M&M Cookie Bars impossible to resist. Here’s how every element works its magic:

All-purpose flour: This forms the backbone of your bars, giving them sturdy yet tender structure so every slice holds together beautifully.
Baking soda: Just the right amount of lift, creating a soft and ever-so-slightly chewy crumb.
Salt: Don’t skip it! A touch of salt brings out all the rich, sweet flavors and makes the chocolate pop.
Unsalted butter (room temperature): The key to unbeatable flavor and those crisp, golden edges that every cookie bar should have.
Light brown sugar (packed): Adds moisture and a deep caramel note to each bite—use it generously for that classic, chewy cookie texture.
Granulated sugar: Balances sweetness and gives the bars their signature tender bite.
Large eggs: Eggs bind everything together and add a lovely richness to the dough.
Vanilla extract: A splash of vanilla enhances every other flavor and rounds out the sweetness.
M&M candies (divided): These gems are the star of the show, adding pops of color and a chocolatey crunch in every bar (plus they’re so fun to decorate with!).
Semi-sweet chocolate chips: Each chocolate chip melts into a pocket of gooey bliss—totally necessary for the ultimate cookie bar experience.

How to Make M&M Cookie Bars

Step 1: Prep Your Pan and Oven

Preheat your oven to 350°F. Grab a 9×13-inch baking pan and line it with parchment paper or foil, letting the edges hang over for easy lifting later. This step makes getting those gorgeous bars out of the pan a breeze every time.

Step 2: Whisk the Dry Ingredients

In a large mixing bowl, whisk together the all-purpose flour, baking soda, and salt. A quick whisk ensures all your leavening and seasoning are evenly distributed, so every bite is perfectly balanced.

Step 3: Cream the Butter and Sugars

Using a stand mixer (or a hand mixer, or even some solid arm power), cream the room temperature butter with the light brown sugar and granulated sugar until the mixture is light and fluffy. This step helps create those tender, chewy edges that everyone raves about.

Step 4: Add Eggs and Vanilla

Crack in the eggs and splash in the vanilla extract, mixing until everything is combined. The eggs give your dough richness and heft, while the vanilla infuses it with warmth and sweetness.

Step 5: Bring It All Together

Now, with your mixer on low, add the dry ingredients little by little, stopping as soon as everything is combined. Over-mixing at this stage can make the bars tough, so just give it a gentle mix until the last trace of flour disappears.

Step 6: Stir in the Mix-Ins

Fold in 1 cup of the M&Ms and all of the chocolate chips with a spatula. Folding by hand preserves the color and “chunk factor” of your M&M Cookie Bars, making sure every square is loaded with treats.

Step 7: Press and Decorate

Press the cookie dough evenly into your prepared pan, smoothing out the top. Sprinkle the remaining M&Ms over the surface and press them in gently—this not only looks gorgeous but lets everyone know exactly what kind of cookie bar awaits.

Step 8: Bake to Perfection

Slide that pan into your preheated oven and bake for 22 to 30 minutes. Look for a golden top, lightly browned edges, and a center that’s just barely set. Let the bars cool in the pan on a rack (this patience pays off when slicing), then lift out, cut, and serve!

How to Serve M&M Cookie Bars

Garnishes

For an irresistibly bakery-worthy finish, sprinkle a little flaky sea salt on top while the M&M Cookie Bars are still warm; it brings out the chocolatey flavors even more. You can also drizzle melted white chocolate or add a handful of extra mini M&Ms right before serving for an extra pop of color and crunch.

Side Dishes

These cookie bars play nicely with so many options! Serve them with a scoop of vanilla ice cream for a true dessert dream team, or pair with fresh berries for a fruity, tangy balance. A tall glass of cold milk or a mug of hot cocoa turns snack-time into a mini celebration, no matter the occasion.

Creative Ways to Present

For parties, slice the bars into bite-sized squares and stack them high on a vibrant platter, or wrap individual portions in colorful wax paper as take-home treats. You can also use cookie cutters to make fun shapes from the bars for birthdays or holidays—those pops of M&M color make every shape look festive and inviting!

Make Ahead and Storage

Storing Leftovers

M&M Cookie Bars stay fresh and chewy for several days at room temperature. Simply place cooled bars in an airtight container with parchment or wax paper between layers to prevent sticking. They’re perfect for packing into lunchboxes or sneaking as a midnight sweet treat.

Freezing

These bars are freezer-friendly! Once fully cooled, slice them and layer with parchment in a freezer-safe container or zip-top bag. They’ll keep their magic for up to 3 months. Just bring a few out to thaw whenever cravings strike or company drops by unexpectedly.

Reheating

If you love that warm, gooey cookie feel, pop a bar in the microwave for 10-15 seconds. The chocolate gets melty and the M&Ms turn delightfully soft—almost like the bars just came out of the oven all over again. Trust me, it’s totally worth it!

FAQs

Can I use different types of M&Ms for these bars?

Absolutely! Flavorful variations like peanut butter, caramel, or mini M&Ms work just as well and let you customize the bars to your mood or occasion. Just keep the volume the same for best results.

What if I don’t have a 9×13 pan?

No worries—an 11×7 pan will give you thicker bars, and an 8×8 pan will work in a pinch, though you may need to adjust baking time. Just watch for doneness in the center before removing from the oven.

Can I make M&M Cookie Bars gluten-free?

Yes! Substitute your favorite 1:1 gluten-free baking flour blend for the all-purpose flour. The texture will be a touch different, but the bars will still be totally delicious and crowd-pleasing.

My bars seem dry—what went wrong?

Dry bars often result from overbaking or mis-measuring flour. Check your oven early and fluff the flour before scooping to avoid packing it down. Baking just until the center is set ensures moist, chewy bars every time.

Do I have to use both chocolate chips and M&Ms?

While the combination is what puts these bars over the top, you can absolutely use just one or the other. Or get creative and add in your favorite candies or nuts for your own signature version!

Final Thoughts

If you’re craving something easy to make, endlessly shareable, and packed with joyful, candy-coated goodness, you owe it to yourself to bake a batch of M&M Cookie Bars. They’re sure to become a star in your baking rotation, and I can’t wait for you to taste how fun and delicious they are!