M&M Cookie Bars

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M&M Cookie Bars!! One of my favorite desserts of all times. And also be warned – one is NOT to be left alone with a pan of these!

M&M Cookie Bars from www.whatsgabycooking.com (@whatsgabycookin)

Is there anything better than a soft cookie in bar form? Where the edges are just lightly golden brown and a tad bit crunchy… and the inside is gooey and soft and melts in your mouth? Let me answer that for you…. no.

M&M Cookie Bars from www.whatsgabycooking.com (@whatsgabycookin)

It doesn’t get better than this when it comes to a quick and easy dessert that literally every single person will love.

M&M Cookie Bars from www.whatsgabycooking.com (@whatsgabycookin)

These bars are my favorite sugar cookie recipe baked up in bar form. A few tips and tricks. 1: use a 9×9 pan. Don’t try and do it in a 9×13 or an 8×8… it won’t be the same. Trust me – there’s a reason I developed it this way! And a glass baking dish doesn’t retain heat the same way a metal baking dish does… so use a metal baking dish!

M&M Cookie Bars from www.whatsgabycooking.com (@whatsgabycookin)

2: don’t skimp on the M&M’s and the sprinkle of salt on top. It really makes all the flavors sing!

M&M Cookie Bars from www.whatsgabycooking.com (@whatsgabycookin)

3: After the baking time – LET THESE SET FOR 2 HOURS. They might look a little under-baked but they need time to finish residual baking once they come out of the oven.

4: proceed with caution once these are baked and cut. I’ve eaten pretty much an entire pan once before and I’m not even remotely exaggerating. Thomas had to remove the last 2 squares from the house because I could NOT BE STOPPED.

Soft Sugar M&M Cookie Bars

4.9 from 12 votes
Prep Time 5 mins
Cook Time 40 mins
Total Time 45 mins
Course Dessert
Cuisine American


  • 1 cup butter melted
  • 2 cup light brown sugar
  • 4 teaspoons vanilla extract
  • 2 large eggs
  • 2 cups all purpose flour
  • 1 teaspoon baking powder
  • ¼ teaspoon of baking soda
  • 1 cup Milk Chocolate M&M’s plus extra for garnish
  • Maldon sea salt optional


  • Preheat oven to 350 degrees.
  • In a large bowl, combine the melted butter and brown sugar and mix with a wooden spoon for 1 minute until combined. Add the vanilla and eggs, making sure to scrape down the sides of the bowl, and mix until fully incorporated.
  • Add the dry ingredients into the bowl and slowly mix until just combined. The batter will be a bit stiff, but that's normal. Fold in 1 cup of the Milk Chocolate M&M’s.
  • Spray a 9x9 metal baking pan (see note above) with baking spray and line it with parchment paper. Spoon the batter into the prepared baking sheet and sprinkle with the remaining Milk Chocolate M&M’s and Maldon sea salt if desired and transfer it into the oven. Bake for 35-40 minutes. Once the bars have baked, remove them from the oven and let cool for at least 2 hours before cutting and serving.


  1. I have been cooking the M&M bars for 45 min and they still aren cooked. Very soupy. What did I do wrong? Followed the re I’ve exactly but it wasn’t stiff when I mixed it. It was very liquidy.

    1. hmmmmm it should def be thick when mixed! Are you sure you added the correct amount of flour? That would be why it wouldn’t thicken up

    2. Same thing just happened to me. I think there is too much butter. Should probably be one stick of butter instead of one cup. One cup is really a LOT of butter.

    3. I had the same issue! I baked for 55 minutes and they never fully set up. Toothpick came out clean once I removed from the oven but when I cut after cooling for 2 hours, not done.

  2. I have mini M&M’s can i substitute with them ? it calls for 1 cup and then sprinkle the top with them before baking. is that another cup or 1/2 cup ?

  3. I tried these today. They are so tasty but very cakey and not so much cookie like in texture. What could I have possibly done different? Baked for fewer minutes?

  4. 5 stars
    Yum! Followed the recipe to a T and they turned out perfectly. Taking them to work with me tomorrow so I don’t eat the whole pan myself!

    1. Love this recipe! But one question, what if you got brown sugar? Would it not work since you call for light brown sugar?

  5. 5 stars
    Made these 3x over the holidays… yes THREE. Lol
    Some gifted, some served when hosting, some hoarded for ourselves…

    Recipe was followed to a T….
    Turned out perfectly each time. No issues.
    Melted the butter in the microwave and it pulled everything together perfectly.
    The flakes of salt on the top are 200% mandatory. They really make this treat amazing!
    One more family function this weekend me while I was asked to bring apps, I’m also bringing some of these

    Thanks for the amazing recipe!

  6. Have you tried using chocolate discs instead of m&m’s? Hope it works ‘cause I just popped them in the oven!

  7. Just made these for an Oscar Party I am having tomorrow night and followed the recipe exactly as stated.
    Melted the butter in the microwave and used a wooden spoon to really mix the butter into the brown sugar. Batter was thickened before it went into the pan.
    They came out perfect and just like you said: looked a little underdone when I pulled them out of the oven and then PUT A NOTE ON THEM NOT TO BE TOUCHED for 2 1/2 hours and that was the crucial part!!
    Agree with another review that the maldon salt is SO necessary to give it the perfect balance in the mouth.
    They are pretty to look at and delicious to eat!
    Thanks! Will definitely make again!

  8. 5 stars
    So delicious and easy. The hardest part was waiting the 2 hours for the bars to cool (as in it was so hard to wait that after an hour I had to try a piece of the edge). The salt sprinkle is key, next time I’ll add more!

  9. 4 stars
    Hi! I made these. The flavor is so delicious and addictive. Mine are really soft. I baked on a lower rack for 36 minutes. I’m not a great baker. I will move up one rack and bake 2 extra minutes next time. These are so easy and were fun to make with a child helper. Thanks Gaby!

  10. 5 stars
    Making these again today! Using red m&m’s for a belated Galentine’s dinner tonight! These are a tried and true, no fail dessert. So glad I found this recipe at Christmas – it’s my go-to! ❤️

  11. Hi, I hope you’re doing well! I’m in NYC and want to bake this while we are sheltering in place. My husband could only find smoked maldon salt at the grocery store (we’re so lucky that we even have access to groceries still; so this is really a ridiculous thing to be concerned about on my part). Will smoked maldon taste ok on these? Also, do you recommend salted or unsalted butter?

    1. unsalted butter is best but if you only have salted that’s fine too! Just omit the salt from the recipe! And smoked salt might be incredible in this!! You could also just leave it out entirely if you don’t want a hint of smoky flavor. Bottom line: it’s gonna be good no matter what you do and stay safe! xoxo

  12. 5 stars
    AMAZING!!! I only had an 8 inch pan, so I baked it for 43 minutes. They turned out fantastic and so easy to put together quickly.

  13. Just made these using jumbo chocolate chips and chopped pecans – insanely good!! Thanks for such a great base recipe Gaby!

  14. Dang it!! I was so excited for these. I made it exactly as recipe calls, baked for 40 minutes in 9×9 metal baking dish and let rest for 2 hours. The edges were crisp but the inside was still so mushy?!?!?! Could it be that we are at 5100 ft elevation? What adjustment should I make.

  15. I have made these twice (following the recipe to a t) and both times the middle has collapsed and still been very gooey! Any suggestions?

  16. I made these last night for the gift bags I put together for our virtual Xmas party this year and and they are AMAZING! I didn’t have a 9×9 pan, but saw another person commented and used an 8×8, I baked for 45 minutes and let them cool for the two hours and they’re perfect! So excited to share these!

    1. that would probably work. Cast iron retains heat REALLY well – so they might actually cook a bit faster. Keep your eyes on them for sure

  17. These are delicious! I have only made them once before but I am making them now to send to my nephew for his birthday. I can’t wait to hear what he thinks after trying them. Also, really easy to make. I did buy the exact 9×9 recommenced pan. I also used Himalayan pink sea salt because that is what I had. These will definitely be a regular baked good in my house.

  18. 5 stars
    These are a fan favorite in my house! I actually make them for people and give them as gifts. Melting the butter makes such a difference with baked goods. Never in 1 million years would I have thought to do that until I read this recipe and you’re a little brownie bites recipe. Amazing!!!

  19. Followed the recipe, cooked for 35 mins and was completely over baked, not moist at all 🙁 but still tasty!
    Should I reduce the time next time? I used a glass tray as I don’t have a metal one, but that can’t be the reason to overbake I assume?
    Also would really appreciate gram conversion in the recipes.
    Thanks !

    1. did you follow the recipe as printed? or was there any type of conversion that you did? any ingredient substitutions?

  20. 5 stars
    In this recipe, is the brown sugar supposed to be packed? I made these and packed it (thinking cookie recipes usually say to do that) and they turned out yummy, but so sooo sweet lol. Almost like caramel. And all the m&m’s sunk to the bottom except the ones I put on top before baking.

    My sweet tooth is pretty intense but how sweet these turned out is a lot even for me lol. I have to imagine I wasn’t supposed to pack the sugar though, right? If you were able to add gram measurements on baking recipes that would be hugely helpful!

  21. 5 stars
    Made these today and only had an 8×8…so I ate a few scoops of batter and hope it makes up for not having the bigger pan

    1. I would cut – that way you can take them out 1 by 1 and eat them as needed!

      unless you’re planning to serve the whole thing… then freeze whole

  22. Gaby, what kind of baking dish do you recommend? Metal vs. glass? I made the snickerdoodle blondie bars in my glass dish and they were gooey in the middle so I am guessing I should make these in my metal pan? Also could this recipe be doubled and cooked in a bigger dish (9×13)?

  23. Unsalted or salted butter?? Gonna try whipping these up when the kiddos take a nap (ha… yeah right they’ll nap!).

  24. Gaby! So delicious! I have a 3- and 5-yr old, and we all made these together. Huge hit from start to finish, and super fun with the Valentines M&M colors!

  25. Love these bars! Question each time I make these the outside gets crispy and the middle sinks while cooking. Any ideas? I use a 9×9 metal pan.

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