Rainbow M&M Cookies.

Soft and chewy cookies filled with colorful M&Ms. These are a cookie jar favorite!

Soft and chewy cookies filled with colorful M&Ms. These are absolutely a cookie jar favorite!

These incredibly addicting cookies are super chewy and, by far, the softest cookie I’ve ever baked.  They completely disappeared when I brought them into work, with some people even asking me if they were store-bought.  Store-bought? The horror!

I adapted the recipe from the famous Cooks Illustrated Chewy Chocolate Chip Cookie.

Rather than melting the butter – as directed in the Cooks Illustrated recipe – I creamed the butter with the sugars and eggs, which produced an exceptionally thick and puffy cookie.  Just the way I like them!   Another trick to get a thick and puffy cookie is to chill the dough.  Like, for hours.  Yup… 30 minutes and to up to 5 days of chilling.

Soft and chewy cookies filled with colorful M&Ms. These are a cookie jar favorite!

The unbelievably soft texture and chewiness to this cookie can be attributed to the extra egg yolk.   Egg yolks are the source behind a cookies soft texture.  This recipe calls for 1 whole egg and 1 egg yolk.  Also credited to the chewiness of this cookie is the brown sugar to white sugar ratio.  This recipe calls for double the amount of brown sugar to white.  So, with double egg yolks and double brown sugar, these babies have double the softness and double the chewy texture!

Make these amazing cookies now and learn why you will use this recipe time and time again!

Rainbow M&M Cookies

Yield: 30 cookies

Print Recipe

Soft and chewy cookies filled with colorful M&Ms. These are a cookie jar favorite!


  • 2 cups + 2 tablespoons all-purpose flour
  • 1/2 teaspoons baking soda
  • 1 teaspoon cornstarch
  • 3/4 cup (1.5 sticks) salted butter, softened
  • 1 cup packed light brown sugar
  • 1/2 cup sugar
  • 1 egg, at room temperature
  • 1 egg yolk, at room temperature
  • 2 teaspoons vanilla extract
  • 1 cup mini M&Ms


Preheat oven to 325F degrees.

Mix the flour, baking soda, and cornstarch in a bowl and set aside. With an electric mixer or stand mixer with a paddle attachment, cream the butter and sugars together. Add the egg, egg yolk, and vanilla and mix well. Gradually add the flour mixture and stir until a dough forms (may take a couple minutes of stirring). Fold in the mini M&Ms.  Do not overmix the dough at any point in this process.

Chill dough for at least 30 minutes (or up to 5 days, covered) in the refrigerator.  Drop by tablespoonfuls onto ungreased baking sheet. Press a few more M&Ms onto the tops for decoration. Bake for 8-10 minutes or until edges are slightly browned. The centers should appear very soft and puffy. Let cool completely and enjoy!

 Sally's Tip: Make sure to keep dough cold at all times while the batches are baking. I kept my dough in the refrigerator in between batches.

© Sally’s Baking Addiction. All images & content are copyright protected. Please do not use my images without prior permission. If you want to republish this recipe, please re-write the recipe in your own words, or link back to this post for the recipe.


Check out some of my other favorite homemade cookie recipes.

Like these Peanut Butter Cup Oatmeal Cookies 

Peanut Butter Cup Oatmeal Cookies-4


And these Sweet & Salty Potato Chip Toffee Cookies.

Potato Chip Toffee Cookies by Sallys Baking Addiction






97 Responses to “Rainbow M&M Cookies.”

  1. #
    Silvposted July 21, 2015 at 11:40 am

    Please could you provide the numger of grams of m&ms needed? I also can only find the normal sized m&ms in the UK – will that suffice?



  2. #
    Jenposted August 5, 2015 at 11:11 pm

    Hi Sally,
    How long should I leave the eggs and butter out for? Looking forward to trying these!


    • Sallyreplied on August 6th, 2015 at 8:39 am

      Until room temperature – I’d say at least an hour. For the egg, set it in a glass of warm water for 10 minutes.


  3. #
    Christineposted October 6, 2015 at 5:32 pm

    The M&M’s melt and get weird coloring everywhere, please help?


  4. #
    Saraposted February 8, 2016 at 6:59 am

    Could I make this recipe with peanut m&ms?
    I have been having difficulty finding a peanut m&m cookie that doesn’t involve a peanut butter cookie base. 


    • Sallyreplied on February 8th, 2016 at 7:43 pm



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