Soft-Baked Monster Cookies.

Super soft and thick peanut butter cookies with oats, chocolate chips, and M&Ms. 

Monster Peanut Butter Cookies - the best monster cookies you'll ever make! @sallybakeblog

“Monster Cookies” are peanut butter oatmeal chocolate chip M&M cookies. For as much as I love peanut butter and oatmeal cookies, it’s quite surprising to see no basic peanut butter oatmeal cookie recipe in my archive.  To be honest, the reason I’ve never shared one with you is because it’s taken me almost 3 months to develop one I’m proud enough to publish. Too flat, too puffy, falling apart, rock hard, too dry, and too sweet peanut butter oatmeal cookies have all made their way in and out of my kitchen lately.  But not this one.  Oh my heavens.  I’ve finally found that “perfect” one.  I am so excited to show you!

As I mentioned above, “monster cookies” are peanut butter oatmeal cookies stuffed to the brim with colorful M&Ms and chocolate chips.  Today’s recipe is unlike most traditional monster cookie recipes though.  It’s more like a peanut butter cookie with oats, rather than an oatmeal cookie with peanut butter.  Still with me?

Also putting these monster cookies apart from the rest is that they are soft-baked. My favorite cookie term! Soft, tender, chewy, and moist in every bite.  Quite unlike the crunchy hard peanut butter cookies you are used to. And finally, my version is stuffed with a variety of M&Ms. Peanut Butter M&Ms, classic M&Ms, and mini M&Ms all paid a visit to my monster cookie dough.

Monster Peanut Butter Cookies - the best monster cookies you'll ever make! @sallybakeblog

Also good to know ahead of time is that my recipe doesn’t make 5-6 dozen cookies like most monster cookie recipes I’ve seen out there that use 3 eggs, 4 cups of flour, 4 cups of oats, 1 pound of butter, etc.  Rather, my recipe uses a fair amount of ingredients and yields just 2.5 dozen medium-sized cookies, so they aren’t actually “monster” in size, but feel free to make them larger.  Oh and bonus: it can all be mixed up in ONE bowl.

It’s an easy, manageable, and quick recipe! One thing I will note: lease use quick oats here. Why? You need the slightly finer size from the quick oats in order to give the cookies a more uniform texture.  Quick oats will act more as a binder in this recipe than whole oats would, since the consistency is more powdery and the oats are smaller in size.  I actually did not have quick oats at the time, so I ground up my oats in a food processor for a quick 10 seconds to break them down.

Like I mentioned, this is a quick cookie recipe! There is no dough chilling needed for these cookies! The dough is quite manageable as is. However, should you bake these cookies with a thinner peanut butter or on a particularly humid day, be sure to chill for up to 30 minutes in the refrigerator.  Cookie dough can be testy. Go by how your dough feels. If it’s too sticky, chill for 30 minutes. If not, just bake.

Helpful tip: the cookies spread just slightly while baking, so you’ll need to press them down a bit a bit with the back of a spoon once you remove them from the oven.  That’s what gives the cookies their crinkled tops.

Let’s discuss their texture. Wow. I baked these on a Saturday and by Wednesday, they were STILL so soft. Why did they last that long? I forgot I had one sitting around in a little baggie (whoops). So, yes. These cookies remain exceptionally soft for days and days. I also found that their peanut butter flavor is enhanced after day 1, too. Just wait until you taste these!

The oats make them unbelievably chewy, the M&Ms give them a pop of color, and we obviously love the combination of chocolate chips and peanut butter. And I love how thick they are! Even after slightly pressing down after they come out of the oven, the cookies are still so thick and hearty.

Monster Peanut Butter Cookies - the best monster cookies you'll ever make! @sallybakeblog

In a world where there can never be too many peanut butter cookies, I’m happy to have a peanut butter oatmeal cookie I can use again and again.  Especially ones that took me a several batches to develop and perfect. It was worth the wait!

Follow me on Instagram and tag #sallysbakingaddiction so I can see all the SBA recipes you make! ♥

Soft-Baked Monster Cookies

Yield: 2.5 dozen

Print Recipe

The best monster cookies ever.


  • 1/2 cup (1 stick or 115g) salted butter, softened to room temperature*
  • 1/2 cup (100g) packed light brown sugar
  • 1/4 cup (50g) sugar
  • 3/4 cup (185g) creamy peanut butter
  • 1 large egg
  • 1 teaspoon vanilla extract
  • 1/2 teaspoon baking soda
  • 1 and 1/4 cups (160g) all purpose flour (measured the correct way)
  • 1/2 cup (40g) quick oats*
  • 3/4 cup (150g) M&Ms (any size or variety)
  • 1/2 cup (90g) semi-sweet chocolate chips


Preheat oven to 350F degrees. Line baking sheet with parchment paper or silicone baking mat.

In a large bowl, using a hand-held mixer or stand mixer with paddle attachment, cream the butter and sugars together on medium speed, about 3 minutes. Mix in the peanut butter, egg, and vanilla (in that order). Scrape down the sides of the bowl as needed. Slowly mix in the baking soda and flour. Do not overmix. Fold in the quick oats, M&Ms, and chocolate chips. If the dough is very soft and unmanageable by hand, chill the dough for 30 minutes before rolling.

Rolls balls of dough, about 2 Tablespoons of dough per ball, onto prepared baking sheet. Press a few extra M&Ms on top for looks, if preferred. Bake for 9-10 minutes - do not bake past 10 minutes. The cookies will appear undone. I too mine out at 9 minutes, which is recommended. Slightly press down the baked cookies with the back of a spoon, since the cookies only slightly spread in the oven. Allow cookies to cool on baking sheet for 10 minutes before transferring to a wire rack. Cookies will firm up as they cool. Store cookies covered at room temperature for up to 1 week. Cookies freeze well.

Additional Notes:

*You may use unsalted butter in this recipe. If so, add 1/4 tsp salt with the flour.

*Please use quick oats in this recipe. You need the slightly finer texture from the quick oats in order to give the cookies a more uniform texture. Quick oats will act more as a binder in this recipe than whole oats would, since the consistency is more powdery and the oats are smaller in size.

© 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.



Do you like oatmeal cookies? Peanut butter cookies?

Next, you must try these recipes:

Soft-Baked Reese’s Pieces Cookies

Soft-Baked Reese's Pieces Butterscotch Cookies-5


Peanut Butter Lovers’ Cookies

Soft-Baked, thick, & chewy Peanut Butter Lovers Cookies. Filled with all of your peanut butter favorites!


Reese’s Stuffed Peanut Butter Cookies

Reese's Stuffed Peanut Butter Cookies. Soft, chewy, and overloaded with peanut butter!





308 Responses to “Soft-Baked Monster Cookies.”

  1. #
    Stephanieposted December 20, 2014 at 11:18 am

    Is it possible to make these into bars instead of cookies? What would the baking time be?



    • Sallyreplied on December 20th, 2014 at 3:02 pm

      Yes– and I’m unsure. I believe this recipe will fit into a 9×9 square pan.


  2. #
    RTposted December 27, 2014 at 3:18 pm

    Hi Sally,

    Where are the recipes? For some reason they are not showing up anywhere!!


    • Sallyreplied on December 27th, 2014 at 3:26 pm

      I was in the middle of updating my website– the recipe should be showing for you now. Happy holidays!


  3. #
    Daveposted January 1, 2015 at 6:48 pm

    After trying to think of different cookies to make for my 4 and 3 year old I started to think about the monster cookies my grandmother use to make when I was little, then I came across your recipe. It seems bang on to my grandmother’s recipe with the exception that she put rasins in her’s sometimes. With the reviews I’m sure I won’t have any troubles making them and hopefully they’ll become a regular staple in our home.


  4. #
    Stephanieposted February 3, 2015 at 3:02 pm

    Seriously amazing cookies. I doubled the recipe and made them a bit larger, and had enough dough leftover to mKe mini ones for my daughters lunchbox. She doesn’t know I put one in her lunch today; I hope she loves them as much as I do! This is my go-to website for the best recipes! You’re truly amazing Sally!


  5. #
    Kristinposted February 24, 2015 at 12:05 pm

    AWESOME!!! Used butterscotch chips instead of chocolate…..hoping these cookies make it through the day!!!


  6. #
    Annetteposted February 24, 2015 at 8:28 pm

    These turned out perfectly! I have never been a big fan of monster cookies because they seemed dry with too much oatmeal and not enough peanut butter. Yours truly are perfection! My little neighbour girls were here helping so there are some happy families with homemade cookies on the street tonight! The rest are being packaged up for mailing. I doubled the recipe with no trouble at all. Thanks so much! I really like your blog because your stuff ALWAYS turns out!


    • Sallyreplied on February 25th, 2015 at 8:56 am

      Thank you Annette!


  7. #
    Paulaposted March 1, 2015 at 1:37 am

    just made these, doubled the recipe and added 1/2 cup each ground pecans, coconut, milk choc chips, pb chips, mini semi-sweet choc chips and rice krispies. Quite possibly the best cookie I have ever made – absolutely delightfully DELICIOUS!! Thank you Sally”s Baking Addition – you are making the world a better place 🙂


  8. #
    Kathrynposted March 23, 2015 at 9:31 pm

    Just made 3 batches of these to take to school for a treat in my son’s 4th grade class end-of-year Reading test. The kids LOVED the “power cookies” as they were called!

    Thanks so much!


  9. #
    Giseleposted March 26, 2015 at 10:29 pm

    Fabulous cookies! Love this recipe. Thanks!


  10. #
    Cathyposted April 6, 2015 at 11:51 am

    I made these cookies for Easter and they were AHHMAZING!!! I did have to bake them a little longer and they came out perfect! My new favorite cookie recipe. Thank you for sharing!!


  11. #
    Jessicaposted May 6, 2015 at 12:27 pm

    Our kids had their first campfire of the year at grandma and grandpa’s last weekend and are on a marshmallow kick. We added 1/2 cup of mini marshmallows and they are devine! Thanks for the great recipe!


  12. #
    C Wongposted May 9, 2015 at 3:59 am

    these cookies turned out very well, added an extra 1/4 cup of quick oats and used both mini and peanut m&ms + semisweet choc chips…thanks for the extra notes about quick oats & cooling time, those details are much appreciated!!!


  13. #
    Pam Duncanposted May 20, 2015 at 2:30 pm

    Yummy! I doubled the recipe as I have a hard time keeping cookies in the house, between hubs and our 3 pre-teen boys. I had to chill the dough, as I overestimated my free time the morning I made the dough–couldn’t bake until the early afternoon. I found the chilled dough a little dry and had to squish it together a bit in order to make a nice ball with the cookie scoop. I used the small scoop and got about 48 cookies, I baked for 8 minutes on parchment, and let sit for 3-4 minutes after removing from the oven. They firmed up a little but remain soft and scrumptious. My boys love them! Thanks, Sally!


  14. #
    Patriciaposted May 30, 2015 at 9:05 pm

    Made these cookies tonight. They are so yummy!! My family loves them. Thank you for the recipe!!


  15. #
    Morgan A.posted June 7, 2015 at 3:58 pm

    Hey, Sally! I make these all the time and my family loves theme! I’m just wondering if they’re supposed to appear undone and still “doughy” in the middle when you break them in half to eat them, or are they just under-baked? Thanks in advance!


    • Sallyreplied on June 8th, 2015 at 9:46 am

      Well, they should be very soft– but also cooked through! Maybe add another minute to the bake time if you make them again Morgan.


      • Morgan A.replied on June 8th, 2015 at 10:31 am

        I added a couple more minutes to the bake time. They look great! I think I’m just impatient about waiting for them to firm up! This is a fantastic recipe! My dad is always asking me when I’m going to make these.

  16. #
    Brandenposted June 17, 2015 at 8:56 pm

    I may have just found my new favorite cookie recipe. Next time I make them I will be doubling the recipe. With my 3tbsp scoop I only got 20 cookies. Not nearly enough for this amount of yum!


  17. #
    Katieposted June 21, 2015 at 12:04 pm

    Hi Sally,

    What kind of peanut butter would you suggest for these Monster cookies? A traditional kind like Kraft, or an all natural that separates like Adams?



    • Sallyreplied on June 21st, 2015 at 3:54 pm

      A traditional kind is best. I prefer Jif or Skippy. But any brand you prefer works!


  18. #
    Mattposted July 8, 2015 at 4:26 pm

    Just spent a “staycation” afternoon with my 12yr. old son making this recipe. My grandmother and I used to spend many a Friday night making monster cookies for friends and family. Many a pleasant memory of baking with her. Now passing on hopeful memories to my son. He made the recipe exactly and they turned out perfectly. Thanks so much!


  19. #
    Emilyposted July 13, 2015 at 7:57 pm

    YUM! Made some “modifications” to try to lower the GI index of these. Used whole rolled oats and whole wheat flour. And, instead of using 1 1/4 cup flour, I used 1 cup and upped the oats to 3/4 cup, instead of 1/2 cup. Also omitted the while sugar completely. They were AWESOME. you would never know I subbed WW flour for regular, or that there was sugar omitted. Next time, I would even consider increasing the oat ratio higher and decreasing the flour ratio accordingly. As for using whole oats, they added awesome texture. My friend even suggested subbing all of the flour for quick oats since they are already so broken down (they would make them a tad slower to digest with more oats). Great recipe!


  20. #
    Charleneposted August 13, 2015 at 10:11 am

    Baked up some of your Monster cookies the other day, all i can say is Yum!!! These were delicious, my kids loved em and so did we! The texture is perfect and all the flavors meld together perfectly! Thank you for sharing this perfect recipe! Love your blog, can’t wait to try out more recipes!


  21. #
    Strong mommaposted August 30, 2015 at 12:16 pm

    Hi I was excited to make these but must have made a few mistakes.  My cookies turned out dry and fragile.  I realized I used regular oats vs quick so that could have been part of my issue.  The other thing undid was used a peanut butter that requires stirring.  Otherwise I followed recipe exacltly.  I used convection bake on my oven and not sure that that was right choice as after 9-10 min cookies barely appeared to be cooked at all.  So then I ended up leaving in for 15 min total.  Thoughts or suggestions?  Thanks!!


  22. #
    Elenaposted November 11, 2015 at 12:52 pm

    I did these, but husband said they are too floury, he expected them to be more of oatmeal flackery, I assume… Despite the fact, that I would need to look for new suitable my husband recipe, I like them very much 🙂 page for future.
    Thank you so much for details and precise process describing.


  23. #
    Delaneyposted January 2, 2016 at 7:45 pm

    Are you kidding me? I didn’t even think I liked monster cookies… These are amazing!!! Thanks for another flawless recipe, Sally! 


  24. #
    Geosominposted January 17, 2016 at 9:05 pm

    These are DELICIOUS. I use some butterscotch chips instead of chocolate chips and threw in some pecans as well. Yum. Thanks!


  25. #
    Sylviaposted February 1, 2016 at 2:54 pm

    These cookies did not turn out at all for me.  I baked them 9 minutes and they did appear not done but that’s what you said.  Then I flatted them with a spoon and let them cool.  They were not done inside and had no cookie texture.  My husband told me to throw them out.  I didn’t want to waste the ingredients so on the second sheet I flattened them before baking.  They were in the oven about 20 minutes before I took them out.  They weren’t even burned on the bottom just slightly browned.  They taste like a regular peanut butter cookie not at all like the monster cookies I’ve had in the past.  I don’t think there’s enough oatmeal and maybe not enough flour.  I don’t know why they turned out for everyone else except me.


  26. #
    Ericaposted February 22, 2016 at 10:53 am

    Can I freeze this dough in formed balls like some of your other drop cookies? They look delicious!


  27. #
    Prabhaposted April 2, 2016 at 1:22 pm

    Hi sally,
         I am glad that I found your website. I started baking at home a few months back only. Your recipies are easy to follow. Thanks for such a clear explanation.  Today I tried this monster cookies. Its a big hit at home. Since I dont get M&M here I used gems (I am in India) and it was good. I have tried some of ur cupcakes also. Everything came out well. Thanks and God bless you and ur family 


  28. #
    KKposted May 2, 2016 at 5:48 am

    These are truly awesome cookies! Some recipes just don’t pan out that I try online but this truly hit the jackpot. I can’t wait to make another batch! 


  29. #
    Shelleyposted May 15, 2016 at 12:50 pm

    Thanks so very much for the wonderful Monster cookie recipe. My daughter and I made a batch and we ate almost all of them, I did take my mom a few of them and she’s in love also! Again, thank you!


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