Addictive Recipes from a Self-Taught Baker

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. It’s taken me almost 3 months to develop a monster cookie recipe that 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.

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.

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!

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 10-12 minutes. The cookies will appear under-baked when you remove them from the oven, but they'll continue to cook for a couple minutes on the baking sheet. Slightly press down the baked cookies with the back of a spoon, since the cookies only slightly spread in the oven.
  4. Allow cookies to cool on baking sheet for 10 minutes before transferring to a wire rack. Cookies will firm up as they cool.
  5. Store cookies covered at room temperature for up to 1 week.

Make ahead tip: 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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© 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.


  1. Just made them…didn’t see the dough needed to be chilled for 30 minutes!
    PSH, no matter – these are amazing cookies!!!
    Thank you & God Bless!

  2. These were soooo yummo!! A new favorite for my family. It is everything we like in a cookie. Thank you so much for putting so much work into a great recipe!

  3. Have you ever tried rolled oats chopped in a vitamix instead of quick oats? Not that these cookies could ever be considered “healthy” despite their amazingness, but the glycemic index of rolled oats is almost 1/3 that of quick oats and they provide much more nutritional value. I’m not a big baker but I’ve tried this in a couple oatmeal cookie recipes and it usually works like a charm. Thanks for the awesome recipe…I’m having a little one in about a month and this was my go-to treat during maternity leave with my daughter. I’d much rather make my own than buy from the store!

    • I often make quick oats from whole oats in my food processor, yes. Much easier than having two large containers of both oats in the pantry.

  4. Hi Sally,

    I made these cookies last night for the nurses that are helping my LPN class with our final clinical rotation (2 more days!!). I’ve been baking for years but always find something off or lacking (in my opinion, no one elses). I love your recipes and know that you would only put the best of the best on your blog…so I made these…followed each letter of the directions…I even weighed my ingredients as opposed to measuring…and all I can say is WOW!

    I ate one because…well because…and they were awesome!! The nurses are going to devour these.

    I think I will never measure dry ingredients ever again…only weigh them!

    Thanks for sharing your recipes and your passion for baking!


    • Great, Nicole! I’m so glad you made these cookies and I just know all the nurses will love them too. As I’ve learned over the years, weighing is certainly imperative!

  5. I double this all the time and end up putting 5 add ins at 1/2 cup each. I use chocolate and/ or peanut butter chips, m&ms, Reese’s pieces, skor bar or Heath bits, and a new favorite…Kraft (I think) makes CARAMEL bits. They add a wonderful chew to the bites that they inhabit. I think I will try the idea from the reader who used a combo of cookie butter and peanut butter.

  6. Sally. I just have to tell you what a hit these cookies have been in my house. I’m AMAZED at the texture. It’s is so originial and I absolutely love it! I will have to play with this to see what other recipes I can come up with!
    My husband is in pilot training and these cookies have been a favorite at quite a few events! Thanks for a great recipe!!

  7. These were great! I made them last weekend when I was at a loss as to what to make when my original baking plans fell through. These were fast, easy and delicious! Everyone enjoyed them, they were gone in no time!
    Thanks for sharing these!

  8. Can’t wait to try these they look so yummy! One question, I’ve been into making my cookies larger these days (actually weigh them each at 2.5 ounces), would I need to increase the baking time? i would still be using the “tall” cookie dough trick. Thanks so much for all of the awesome cookie recipes. Can’t wait to wow my coworkers!

    • I would still make sure your cookie dough balls are nice and tall, yes. I’m unsure of the exact baking time, but it will surely be a few minutes longer. Enjoy, Diane!

  9. Dear Sally, I have decided after making and baking many of your recipes that we need to be friends. Lol I find myself always checking with your website for “inspiration” or ways to help my create my inspiration dessert of the moment. (Is there really any need for other food groups??!) My newest experiment was the “monster cookies” omg….really Sally…really?!?!?!?! Was it necessary to post such an amazing recipe?!?! I have made a “batch” twice in 2 days….not helping the waistline. Lol anyway all this long winded – Ness to say…bravo! “Sallysbakingaddiction” has become my addiction!! I beg to to keep going lol!

  10. PS. White chocolate chips are my only add in….*heavenly sigh*

  11. Quick question: I’m not seeing an acidic ingredient here, so why baking soda and not baking powder?

  12. Made these last night..I have a new go-to cookie! 😀 So soft, we all just loved them! Thanks!

  13. Awesome!!!! My daughter made these tonight for “PI” day in her Algebra class tomorrow but I am not sure if they will make it till tomorrow!! Thank you.

  14. I have these in the oven right now – I can’t wait to see how they turn out. I like your idea of using peanut butter M&M’s…sounds dangerous.

    This recipe should be awesome. Thanks for all the detailed instructions as well – they really do help when you’re just a casual baker at home. Thanks again 🙂

  15. These. Are. AMAZING. Wow. I love love love them. Next time I make them, I’m going to sub in Reese’s Pieces for half of the M&Ms… I’m a peanut butter addict! I also prefer mini M&Ms to the regular size ones.

    I made this recipe to help fulfill one of the goals on my list- to try fifteen new dessert recipes. This is my favorite recipe by far! Thank you so much!

  16. I made a test batch of these today, as I am planning to make them to bring to my family’s Easter gathering. I used Easter colored M&Ms and they were delicious and adorable! I can’t wait for my family to try them when I make them again this weekend. Thanks for such an easy and delicious recipe!!

  17. These were a huge hit at the party I took them to last night! They were more peanut butter-y than I was expecting, but after tasting them, the peanut butter is a GOOD thing! Great recipe.

  18. Hi Sally, I made these and they are really good. Very easy to make. I did add an extra 1/4 cup of quick oats. I flattened before baking, don’t like puffy cookies. My son loved them, too! Oh, I used mini M&M’s and mini chocolate chips. Delicious!

  19. I recently tried the soft baked monster cookies, and let me say that they are amazing! They are a little time consuming if you are making several batches due to the cooling time needed, but totally worth it!

  20. Can you substitute cookie butter for the peanut butter?

  21. Hi Sally,

    I’m a girl from Australia who baked this delicious cookies just yesterday! My whole family is obsessed with Peanut butter – including me! So this recipe was a big hit in my household. I added a little extra peanut butter to the recipe since my family loves it so much, and it worked out!

    Keep doing what you do,

    Love Ella xxxx

  22. These are delicious! No more to be said

  23. This is my family’s all time favorite recipe. Thank you so much for sharing. The first time I made these, we actually didn’t have M n Ms, so I used half a cup of Heath, half a cup of white chocolate chips, and a fourth of a cup of semisweet chocolate chips instead of the M n Ms and chocolate chips. People tell me they’re the best cookies they’ve ever had, and they’re the only cookies my health freak older sister will eat. If I even mention the word monster cookie they all get excited and they’ve never lasted longer than two days. So again, thank you for being such a fabulous baker and for sharing your recipes:)

  24. I just made a double batch of these with my 4 year old. We “used up” all of the leftover Easter, valentines, Christmas, (ahem…) Halloween chocolate candy by chopping it all up and throwing it in. Yum! You never know what you’re going to get in each bite. And I might also have put a sprinkle of coarse salt on top of the cookies. Oopsie! The dough in your recipe is dynamite, thanks!

  25. This is the second cookie recipe I’ve tried from your blog that didn’t turn out. The cookies are not even golden brown at 9 minutes. These look nothing like your photo and are not even close to any monster cookie I’ve made before. Too few oats and too much flour.

    • Hey Shannon! I explain in the post that these cookies are peanut butter cookies with only a few oats. Much different from other Monster Cookie recipes – so sorry they did not turn out for you.

  26. Maybe you used non-processed (not quick oats) oats like I did?

  27. Hi Sally. I found this recipe on pinterest and gave it a go. My cookies looked exactly like yours and everything else was the same except that I didn’t use the quick oats and skipped the step of milling them in my Vitamix. I did give them a few rough chops to braak them into bits and used a scant 1/2 cup instead of the entire half cup. And they did not turn out well. I followed the directions EXCEPT for heeding your caveat about NOT using unprocessed (old-fashioned) oats and it came back to bite me. I probably should have left the oats out. The flavor was fine but the cookies were too dry and crumbly (and I’m one of those fanatically precise bakers who weights my dry ingrediants instead of measuring them by volume). It may be that others like this texture and it’s just not to our family’s liking, but my “eat everything” 20-something kids and hubby said they seemed like they had “sawdust” in them (I’m sure it was the traditional oats) and proclaimed it was not a “keeper” receipe. I share this so folks will know, before they make this, that it’s not a tender, moist peanut butter style cookie, and so they know NOT to use traditional oats in their cookies unless they are seeking a very crumbly, dry cookie (I say “dry” even though the inside was moist and slightly underbaked). I suspect it might be a good cookie without the oats (or actually using the quick oats like you told us to use). My question for you is: are these cookies dry and crumbly in texture (even when slightly underbaked) even with the quick oats or did you find the texture offputting when you only when you used traditional oats in your experimentation?

    • Hi Robin – no, these cookies are not supposed to be dry and crumbly at all. They are supposed to be soft and tender, with maybe a little crumb but not much. I advise you to measure the ingredients precisely and use quick oats – you may wish to try my regular peanut butter cookies instead.

      • I think that sometimes, it’s my measuring that is the problem. I always weigh my dry ingredients, and sometimes, I think that when I do that with a traditional recipe that uses volume measurements, the difference creates the problems (this never happens to the recipes that start off with the ingredients measured by weight, such as grams of flour, etc.). This is the website that I use:
        I think the quick oats is likely the biggest “boo boo” on my part (yes, you warned us about that!), and my precise measuring with a traditional (measurements by volume, the American way) likely made that worse. Being this precise and using the wrong oats, is likely what made these peanut butter “sawdust” cookies! For all of the folks who are going to make this recipe, use traditional volume measurements (cups not grams!) and use the quick oats as we were advised. Doing it my way will ensure it’s a flop (not the recipe, apparently, but your end results). 🙂 Sharing my misery to prevent others from the same result. 🙂 Thanks Sally.

  28. This is a MARVELOUS recipe!!!!!! Thank you so much!

  29. Oh, these look so good! Excuse me as I run into my kitchen and check to see if I have all of the ingredients!

  30. Sallyy, thanks a lot for sharing this recipe, i tried it and my cookies turned out perfect!! 🙂

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