Soft-Baked Monster Cookies

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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: please 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

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


  1. Preheat oven to 350F degrees. Line baking sheet with parchment paper or silicone baking mat.
  2. 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.
  3. 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.
  4. Baked cookies freeze well for up to 3 months. Unbaked cookie dough balls freeze well for up to 3 months too. Bake frozen cookie dough balls for an extra minute, no need to thaw. Click here for my tips and tricks on freezing cookie dough.

Recipe 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.

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All Comments

  1. 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!!

  2. 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.

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

  4. 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.

  5. 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 

  6. 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! 

  7. 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!

  8. Doubled the recipe and used a full sized icecream scoop to measure out my cookie dough to make my cookies all monster size. I flatted the cookies slightly in my hands before putting them on the parchment paper. Baked them for 15 minutes since they were larger and then let them rest on the cookie sheet for 10-15 minutes.

    I used crunchy peanut butter (didn’t have smooth), peanut M&M’s, smarties and Reese’s peanut butter chips (husband ate all my chocolate chips).

    Turned out fabulous. Thanks a lot Sally! Greatly appreciated.

      1. Smarties in Canada and the UK are candy coated chocolate pieces, like m&m’s but better. The candy that you’re talking about is called Rockets here.

  9. I know this is an old recipe but I wanted to leave a comment regardless. This is the perfect recipe for people who think they don’t like peanut butter cookies! My main complaint has always been that they are dry and hard…not so anymore! I followed the recipe except I had to substitute 1.5 teaspoon of baking powder for the baking soda. It came out soft and moist just as you described it!!!!!
    I did change the add-ins to suit my taste and what I had. I used chocolate chips, dark chocolate covered raisins and broken up banana chips. These are supposed to be a present for a friend but I might have to make a second batch is she’s going to get any! Thanks for the awesome recipe. I will definitely be making again!

    1. Oh I did want to say one more thing. i flattened and prettied them up before baking. This worked fine since, as you said, they spread very little.

  10. A few summers ago, I found a monster cookie recipe online, baked up a big batch, and they were a HUGE hit.  DELICIOUS!  And of course, I can not, to this day, find the blog that I got that recipe from!  I have been on a search for an equally delicious monster cookie recipe and have tried numerous, none of which came close to comparing to the original recipe.  Until today.  I rarely leave comments but I absolutely had to this time.  If you are looking for a really amazing Monster Cookie Recipe, look no further.  These things are AMAZING.  I think they even beat out the first recipe I made so many summers ago.  So this time, I am SAVING the recipe.  Thank you for this delicious treat!!

    *I did have to bake mine for 11 minutes; every oven is different.

  11. Best cookie recipe!!This is my first time reviewing a recipe….I’ve used tons of online recipes but never felt the need to review until I made these little bits of heaven! These are hands down the best cookie I’ve ever baked! And I’ve baked a lot!

  12. Ever since my roommate showed me this recipe 3 years ago, I would probably have used it more than 20 times. I LOVE soft baked cookies and the PB and Chocolate is to die for. This is the most precise and repeatable recipe I’ve ever come across. Thank you Sally for sharing it!!!!!

  13. These are by far THE BEST monster cookies ever! They are my 7 year old’s favorite cookie. Today, I am making them slightly larger and sandwiching chocolate ice cream between them. Yum! I do make a few changes. My husband does not like oatmeal cookies, so I use Rice Krispies in place of the quick oats. I also use either peanut or peanut butter M&Ms and super chunk peanut butter. (We love out peanuts and am peanut butter in this house!)

    Thank you for this perfect recipe!

  14. I’m relatively new to baking and I’ve tried out several different cookie recipes. This one wins, hands-down, in terms of simplicity and deliciousness! It’s so easy and the cookies might just be perfect! This Will be my go-to recipe for cookies and next time I will double the recipe and freeze the extras as recommended. Thanks Sally! You’ll make a baker out of me yet 😉

  15. I have been on a quest for the perfect monster cookie recipe. This was definitely up there. They don’t disappoint on the promise to come out soft. The only reason I wouldn’t say these are my perfect monster cookie is that for my preference they didn’t have enough oatmeal. They were more like thick peanut butter cookies with M&M and chocolate chips. But they were still delicious. Definitely will at least be in my rotation, even though I am still looking for what I consider the “perfect” monster cookie!

  16. I made these this evening for a bake sale. I added 1/4 cup of each M&M to make 3/4 cup ( plain, peanut butter & peanut) I baked them for 9 minutes, cooled on pan for 10. Just came out dry & bland. Will try again another time.

  17. First off, you are my go to place for recipes. I love that you give the weight measurements for ingredients & I know when I make one of your recipes, it will be delicious. I did have a question about this recipe. The cookies tasted great, but when I cooked them, they were still in the same ball shape. The next batch, I flattened before cooking & the looked exactly the same when I finished cooking them. No spread at all. They were really good still & I want to make they again. Do you have any advice on where I may have went wrong? Thank you!!

    1. Hi Tiffany! No worries here, all I would do is reduce the flour the next time you make these. Sometimes cookies spread too much, sometimes they don’t spread at all. My solution is always the flour. I would reduce down to 1 cup when you make them again.

  18. Hi Sally. 🙂 I like this recipe a lot. Something I did different though was substitute 1/4 cup of smooth peanut butter for crunchy. I find it adds a bit more of a nutty undertone.

  19. I am also a total cookie snob/connoisseur and these cookies were to die for. Perfect texture. Thick and soft. The only thing I did differently was I used cake and pastry flour because I had run out of all-purpose. Was already halfway into the recipe when I realized so their was no turning back. To my surprise they turned out amazing!! Thanks!!

  20. I’ve made these for years now and they are loved every time. One thing I have noticed is the flavour is optimal with Quaker golden syrup flavour quick oats (as sold here in the UK) and peanut M&Ms. Also I make them small (1-2 M&Ms per cookie) and I don’t press down on them, so they stay as more spherical bonbon type treats which seem a little more dainty and diet friendly 🙂 They are so easy and delicious, seriously the best cookie recipe ever 

  21. My daughters boyfriend is coming for Christmas and his favorite is Monster Cookies. I love baking but have never made these before. 
    First off, these cookies are amazing in all ways. Soft and delicious.  I tend to not make “big” cookies. I enjoy a smaller, pretty cookie.  I actually got just over 40 cookies from this recipe. I also dotted the top with 1 red or green M&M and smooshed the cookie down slightly as Sally recommended. 
    The presentation is beautiful but most importantly, a scrumptious cookie.  Thank you, Sally. 

  22. This is the second time I’ve tried to make these cookies. I’ve been baking for years, and these do not spread at all. They are dry and very fragile. Unfortunately won’t be making them again with this recipe.:(

  23. The dough was quite oily (from the peanut butter?) and somehow crumbly at the same time, and the chips and M&Ms didn’t stick to it, making it hard to make a ball. Proportions also seemed a bit off, there didn’t seem to be enough dough and too many chips and M&Ms. I didn’t have parchment paper to bake on. Not sure what difference that would make. They didn’t spread out, like many have said. Still tasty, though!

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I’m Sally, a cookbook author, photographer, and blogger. My goal is to give you the confidence and knowledge to cook and bake from scratch while providing quality recipes and plenty of pictures. Grab a cookie, take a seat, and have fun exploring! more about Sally