Chewy M&M Cookie Bars are chocolate chip cookies baked in bar form. Ooey, gooey, chewy, and filled with chocolate, these bars are irresistible. They are customizable based on occasion or holiday and are the PERFECT impressive treat to bring to any gathering!

What Are Cookie Bars?
Cookie bars are basically cookies baked in bar form. They are a mix between a cookie and a brownie. These are thicker and chewier than a classic blondie though!
You'll make your cookie batter just as normal, but you'll spread all of the dough into a 9x13 inch pan. Then, you'll bake these bars until they are golden brown.
Do not attempt to make this recipe into cookies, as they will not bake properly due to ratio of baking soda, dry ingredients, and wet ingredients. If you're looking for a cookie recipe, Massive Chocolate Chip Pecan Cookies are calling your name!

Ingredients
- All purpose flour: Regular, all purpose flour works beautifully in this recipe. It provides structure while still allowing these bars to be oooey and gooey rather than cakey in texture!
- Corn starch: Corn starch is one of my favorite ingredients in cookies. It helps them to be soft and tender, and the same goes for cookie bars.
- Baking soda: Baking soda is essential for these cookie bars. Its helps them to rise to be tall and also impacts the texture.
- Salt: Salt brings out the sweetness and aids the classic chocolate chip cookie flavor we all know and love!
- Unsalted butter: Using unsalted butter allows you to adjust the salt in the recipe yourself. If you need to use salted butter, leave out the salt in the recipe. Make sure to use room temperature butter to ensure your bars come out soft and chewy.
- Granulated sugar + light brown sugar: These two contribute to structure, moisture, and flavor. The combination aids for the best impact. Make sure to pack your light brown sugar into the measuring cup when measuring!
- Vanilla extract: Vanilla extract contributes to the flavor in these bars. Though there is only ½ of a tablespoon, its impact is mighty!
- Eggs: Eggs add to the chewy texture in these bars. Make sure to use room temperature eggs. Simply leave them out for 1-2 hours before baking or place them in a bowl of warm water for 10 minutes before using.
- Chocolate chips: I use a combination of regular and mini semi sweet chocolate chips. Feel free to use any size and/or flavor you would like!
- M&Ms: You'll see patriotic M&Ms in these pictures for the 4th of July, but any color or flavor of M&M will be fabulous.

M&Ms and Chocolate
The best part about these chewy M&M cookie bars is how customizable they are. You can use any color, size, or type of M&Ms you would like. You can use mini M&Ms, dark chocolate M&Ms, peanut M&Ms.... whatever you have or whatever the occasion calls for!
The same goes for the chocolate chips. I prefer to do a combination of mini and regular semi sweet chocolate chips, but you are more than welcome to do white chocolate, chocolate chunks, or any other type or form of baking chocolate!

Baking Cookie Bars
Here are a few of my tips and tricks for perfect chewy M&M cookie bars.
- Pan Size: I HIGHLY recommend using a 9x13 inch pan. Using a smaller pan will require a longer baking time and will likely brown the edges and top before the inside is properly cooked. A larger pan will create thinner bars and will require a shorter baking time to ensure that they are not overbaked.
- Glass vs. Metal Pan: I bake these bars in a glass pan, but you can use a metal pan. You'll probably need a few less minutes in the oven since metal will trap more heat. Using a metal will likely create crispier edges.
- Bake Time: Bake these bars until they are golden brown around the edges and light golden brown towards the center. A toothpick inserted into the center should come out mostly clean... not clean. These bars are meant to be gooey and chewy, and overbaking them will lead to a drier, cakier texture. The bars will continue to cook as they cool.

FAQ
Room temperature butter is crucial for best results in this recipe. Room temperature butter is cool and slightly firm to the touch. You should be able to push into the butter without breaking the butter stick. It should not be slimy, greasy, or melty, but it should be soft. Simply leave your butter out 1-2 hours before baking. If you forget, cut your butter into tablespoons. Place the pieces in the microwave for 15 seconds before flipping each piece over and microwaving for 10 seconds. Repeat this process in 5 second increments until your butter reaches the proper consistency.
Do not attempt to bake bars into cookies. The ratio of ingredients is suited for these to be baked into bars.
Store cookie bars at room temperature for up to 3 days. You'll want to store them covered or in an airtight container to maintain freshness. The bars will lose moisture as they sit. You can freeze these bars. Wrap the bars in cling wrap before placing them in a bag or container for up to 4 months.
Other Recipes
- Massive Chocolate Chip Pecan Cookies
- Homemade Ice Cream Cookie Sandwiches
- Edible Chocolate Chip Cookie Dough

Chewy M&M Cookie Bars
- Prep Time: 15 minutes
- Cook Time: 45 minutes
- Total Time: 1 hour
- Yield: 9x13 pan 1x
- Category: Cookies, Cookie Bars, M&M Bars
- Method: Bake
- Cuisine: American
Description
Chewy M&M Cookie Bars are chocolate chip cookies baked in bar form. Ooey, gooey, chewy, and filled with chocolate, these bars are irresistible. They are customizable based on occasion or holiday and are the PERFECT impressive treat to bring to any gathering!
Ingredients
- 3 cups (420g) all purpose flour, spooned and leveled
- 1 tablespoon (9g) corn starch
- 1 teaspoon (5g) baking soda
- ½ teaspoon (4g) salt
- 1 cup (220g) unsalted butter
- 1 cup (230g) light brown sugar
- 1 cup (200g) granulated sugar
- ½ tablespoon vanilla extract
- 3 large eggs (150g), room temperature
- 1 cup (180g) chocolate chips (180g)
- ½ cup (100g) mini chocolate chips
- 1 ½ cup (270g) M&Ms
Instructions
- Preheat your oven to 325 degrees Fahrenheit. Line a 9×13 baking dish with parchment paper and spray with cooking oil to ensure the bars come out cleanly.
- In a medium bowl, whisk properly measured all purpose flour, corn starch, baking soda, and salt together.
- In a large bowl with a hand mixer or the bowl of a stand mixer that is fitted with the paddle attachment, mix room temperature butter, light brown sugar, and granulated sugar together until smooth. Mix for about 3-4 minutes until the mixture is lighter and color and slightly fluffy in texture.
- Add vanilla extract to the batter before adding the eggs one at a time. Thoroughly mix between adding each egg to make sure the batter is smooth and fully combined. Scrape down the sides and bottom of the bowl as necessary.
- Slowly add the dry ingredients to the wet while mixing on low speed. Scrape down the bowl as needed. Do not overmix the batter- just mix until the dry ingredients are incorporated.
- Add chocolate chips and M&Ms to the batter and mix until combined. Batter will be very thick.
- Transfer the batter to the prepared pan. Spread the batter with the knife to make sure the bars cook evenly. Top the batter with additional chocolate chips and/or M&Ms as desired.
- Bake for 35-45 minutes or until the sides of the bars are deep golden brown and the middle is light golden brown. A toothpick inserted into the center should come out mostly clean with some crumbs and batter. The bars will continue to cook as they cool. Allow the bars to cool before slicing.
Keywords: Cookie Bars, Chewy Cookie Bars, Thick Cookie Bars, Holiday Cookie Bars, M&M Bars
Violet says
These cookie bars are so good! I just made a double batch of them for Christmas Eve with holiday M&Ms! I’m gluten-free so I used Cup 4 Cup flour instead of regular flour and they still turned out fantastic. Definitely recommend giving this recipe a try, you won’t regret it!
★★★★★
Elise says
Yay!! I'm so glad to hear that the substitution worked well! Thank you so much for trying it out and leaving such a kind review!
Jessica says
These came in SO handy when I lost my blondie recipe right before Christmas! They are so easy (due in large part to Elise's instructions) and they come together almost instantly. I made a half recipe in a 9" square pan and used red and green M&Ms for the holiday season - they came out spectacularly. Thank you, Elise!
★★★★★
Elise says
Thank you so so much, Jessica! I love that this recipe is joining your holiday season! Sending my best wishes your way!
Christina says
Oh my goodness! These bars are so delicious! The recipe was very easy to follow and these bars are my new go-to. They remind me of my fave cookie bar I used to get at Starbucks. So soft, chewy and yummy.
★★★★★
Elise says
Yay! Thank you, Christina! I love these bars and am so glad to hear that you are enjoying them too!
Monica Duffy says
Love this recipe! I did not want to bake it right away, so I made the dough, refrigerated it for 1-2 hours, then let it sit for a bit before baking it. My family approved! I used green and red M&Ms to make it a Christmas dessert. I’m excited to bake it again!
★★★★★
Elise says
Thank you for this comment, Monica! I'm so glad to hear that you were able to make the dough ahead! Thanks for sharing!
Chef Cookie says
Thank you for this recipe. I am a professional baker and I have made these a dozen or so times with just a few tweaks. One of the changes I made was to add a little more salt to balance out the sweetness from the add ins and it made a huge difference.
★★★★★
Elise says
This makes me so happy to hear! Thank you for such a kind message! So glad to hear you have enjoyed these cookie bars!
Stéphanie says
These M&M cookie bars are the favorite of my son’ s kindergarten class! The children (and so the their teacher !) like it so much that It has become an habit to cook some before each holiday period.
I have also cooked them with the children when they had their «American day » at school. We had a lot of visitors coming from the other classes..😉😉
★★★★★
Elise says
Yay! This makes me so happy, Stéphanie! It's so fun that these cookie bars were able to join your son's class. Thank you for trying this recipe and leaving such a kind comment!
Hillary Hooper says
In the last year I have tried countless cookie recipes and I have loved 2. Only 2. This was one of them. These bars came out so delicious and stayed well for days and now I’m excited to keep making them for years to come. Thank you so much for this recipe!
★★★★★
Elise says
This is such a compliment, Hillary! Thank you so much for such kind words!
Morgan S. says
These were a super huge hit at the Friendsgiving party I brought them to! I decided to put mini m&ms on top for an extra pop of color! I really enjoyed these bars and can’t wait to make them again! Thanks for the 5-star recipe, it’s a keeper!
★★★★★
Elise says
This makes me so happy! Thank you Morgan!
Cathleen says
I just made these bars....they are so yummy. I did green and red M&M's....thanks so much🎄
★★★★★
Elise says
Yay! Thank you so much, Cathleen!
Shaylee says
Made these for a cookie contest in the neighborhood and won! They are so thick, soft, chewy, and chocolatey. Delicious! Will be making them a lot more.
Elise says
Yay! This is so exciting, Shaylee! Thank you for sharing!
Julie says
OMG!! These are absolutely amazing!! My daughter and I just made these for the first time and I don’t even know what to say! We did NOT let it entirely cool down before cutting a few pieces out to try. ☺️ I definitely recommend these for such a tasty and festive cookie bar! We used the Christmas M&M’s and they’re just so festive and perfect!
Thank you so much for sharing the delicious recipe for us all! 💞
Elise says
Yay! Thank you so much, Julie! Glad you enjoyed these!
Beverley Doughty says
I made these for thanksgiving and they were a huge hit, so easy to make, recipe was super easy to follow, I had messaged Elise for the recipe and she was so sweet and sent it to me , thanks Elise for sharing, love following you and can’t wait to make something yummy of yours for Christmas 😊
Elise says
This is so kind, Beverley! Thank you for giving the recipe a try!
Alycia Zuniga says
This recipe caught my eye the moment I saw it. If you love cookies as much as I do you will love this recipe. I was so excited to re-create this treat! Elise makes this recipe so easy to follow and understand which is a big plus for me since I am beginning my baking journey. I used green & red M&Ms for Christmas time and they were perfect. My family absolutely loved them! Super soft and chewy which we love! Already making more for this weekend. Followed her instructions and they turned out great! So happy I found this recipe!
★★★★★
Elise says
This comment means the world, Alycia! Thank you so much and glad you enjoyed the recipe! Happy Holidays!
Joanne MARTIN says
So delicious have made these 2 times already
Already a family favorite
Will be making these often!
★★★★★
Elise says
Thank you so much, Joanne! So excited to hear this!
Amy Williams says
Perfection … and easy, too!! This one is a keeper .
★★★★★
Elise says
Means the world, Amy! Thank you!