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! These cookie bars are on par with my famous cheesecake cookie bars. You may want to check those out as well!

An overhead shot of 16 square Christmas MM Cookie Bars


 

Why I Love This Recipe

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.

It doesn't get better than cookie bars when it comes to a quick and easy dessert that literally every single person will love. These cookie bars are my favorite sugar cookie recipe baked up in bar form. You all know how I love the giant M&M cookies and these are just the perfect bar form for that perfect cookie!

Ingredients & Substitutions

Mise-en-place with all the ingredients to make m&m cookie bars
  • Butter
  • Light Brown Sugar
  • Vanilla Extract
  • Large Eggs
  • All Purpose Flour
  • Baking Powder
  • Baking Soda
  • Christmas M&M’s
  • Maldon

*For a full list of ingredients and instructions please see recipe card below.

A glass mixing bowl with melted butter and brown sugar.

Step 1: Preheat the 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.

A glass mixing bowl with a mix of melted butter and sugar, with two eggs added but not mixed in yet.

Step 2: Add the vanilla and eggs, making sure to scrape down the sides of the bowl, and mix until fully incorporated.

A glass mixing bowl with wet ingredients and dry ingredients just added.

Step 3: Add the dry ingredients into the bowl and slowly mix until just combined. The batter will be a bit stiff, but that's normal.

A glass mixing bowl with M&M cookie batter with red and green M&Ms just added.

Step 4: Fold in 1 cup of the Milk Chocolate M&M’s.

A square baking pan with M&M cookie batter and topped with red and green M&Ms.

Step 5: 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.

A square baking pan with M&M cookie square baked in it.

Step 6: 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.

Cut these into squares once cooled, and store in an airtight container for a few days. You can also store in the fridge to keep them longer, about two weeks.

We have not had leftovers for these in our household! However, if you want to freeze them, store these bars in a freezer bag or airtight container for about 3 months. Defrost in the fridge or outside to serve.

Tips & Tricks

1: Use a 9x9 pan. Don't try and do it in a 9x13 or an 8x8... it won't be the same. Trust me - there's a reason I developed it this way! And a glass or ceramic baking dish doesn't retain heat the same way a metal baking dish does... so use a metal baking dish! And 8x8 (while it's the same shape is only 64 square inches and a 9x9 is 81 inches. So that will WILDLY affect baking time.

2: Don't skimp on the M&M's and the sprinkle of salt on top. It really makes all the flavors sing! If you want to add more M&M's mid bake, that will ensure they don't fall to the bottom of the pan.

3: After the baking time - LET THESE SET FOR 2 HOURS. These cookie bars 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 cookie bars 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.

A glass bowl with red and green M&Ms with some M&Ms outside the bowl on the counter.

FAQs

What is the difference between cookies and cookie bars?

Cookie bars are somewhere cakes and cookies. A great and easy way to make a big batch, and the thickness gives them a nice gooeyness. While not all cookie recipes may be suitable for cookie bars, this is a great one! Thickness is also important when baking bars, too thin and it will be too crisp, too thick and the edges will be brittle by the time the center bakes.

Can I add other things to these cookie bars?

Yes! Add nuts, pretzel, chocolate chips- all perfect additions to these bars.

Similar Recipes

If you tried this recipe, please leave a 🌟 star rating and let me know how it goes in the 📝 comments below. Thanks for visiting today

Soft Sugar M&M Cookie Bars

Author: Gaby Dalkin
4.9 from 38 votes
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!
Prep Time 5 minutes
Cook Time 40 minutes
Total Time 45 minutes
Course Dessert
Cuisine American
Servings 16 bars

Ingredients
  

  • 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

Instructions
 

  • 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.

Notes

  • 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!
  • Don’t skimp on the M&M’s and the sprinkle of salt on top. It really makes all the flavors sing! If you want to add more M&M’s mid bake, that will ensure they don’t fall to the bottom of the pan.
  • 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.

Nutrition Information

Calories: 339kcal | Carbohydrates: 48g | Protein: 3g | Fat: 15g | Saturated Fat: 9g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 3g | Trans Fat: 0.5g | Cholesterol: 53mg | Sodium: 160mg | Potassium: 66mg | Fiber: 1g | Sugar: 35g | Vitamin A: 414IU | Vitamin C: 0.1mg | Calcium: 62mg | Iron: 1mg
Tried this Recipe? Tag me Today!Mention @WhatsGabyCookin or tag #whatsgabycooking!

Photography by Matt Armendariz / Food Styling by Adam Pearson

102 Comments

  1. 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! ❤️

  2. 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!

  3. 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!

  4. 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!

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

  6. 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!

  7. 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?

    1. Made these today and after 45 minutes they are very soupy in the middle. Bought a 9x9 pan and used parchment paper. Batter was thick as recipe stated it would be. Not sure what I’ve done wrong?

  8. 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?

  9. 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 ?

  10. 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.

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