Soft-Baked Monster Cookies

Jump to Recipe

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.

Did you make a recipe?

Tag @sallysbakeblog on Instagram and hashtag it #sallysbakingaddiction.

© 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. Some of the links above are affiliate links, which pay me a small commission for my referral at no extra cost to you! Thank you for supporting Sally’s Baking Addiction.


All Comments

  1. I love these cookies. They are soft and rush. I doubled the recipe, next time I may use crunchy peanut butter, or use pecans. I like the nutty flavor to break up the sweetness. Loved the texture of these cookies!!!

  2. Does this recipe require a jiff or Skippy type pb with note oils and sugar added? I used all natural (stir type) and my dough (and cookies) were dry, Crumbly, and lacking flavor. Not so great.

  3. My neighbor made these last year for Halloween and they were so delicious, one of my favorite cookie recipes – can’t wait to make a double batch of them this weekend!!

  4. I’ve been making these cookies for a year now and everyone who tries them, loves them. I always double the batch because they go so fast. My son took some to a neighbor as a thank you because he was so proud of them. My mother in law popped in one day and was hoping I was making these cookies one day because she loves them. I use mini m&m and here is the kicker. If your store carries salted caramel chips, use them. They are very good. This is one of my go to recipes.

  5. Hi Sally, I’m hoping to make your monster cookies and I came across your recipe in your cookie addiction book as well as this. The one in the recipe book states to use whole rolled oats while these recommend instant ones. Can I know what will be the difference? Thank You!

    1. These peanut butter cookies have less oats in them, so they’re more of a peanut butter cookie with some oats. The monster cookies in the cookbook are more like oatmeal cookies with a little peanut butter. 🙂

  6. What a great recipe! I have made these cookies dozens of times and everyone always raves about them. I will be adding them to my Christmas cookie repertoire for holiday gifting. I will use the semi-sweet chocolate chips as well as mini red and green M&M’s.

  7. These were THE best monster cookies I’ve tried, thanks so much for the recipe! I would recommend not using peanut butter m&m’s and instead use original like the recipe called for. I wanted them to be super peanut buttery and its a bit overkill since the cookie itself is really peanut buttery. I made them for my kids class Christmas party and they were a hit; thanks again! 

  8. These are the best monster cookies ever.  I like them so much better that the “original” monster cookie recipe that I had been baking.  I like to use 1/2 semi sweet chips and 1/2 milk chocolate chips, and 1/2 peanut butter M&Ms and 1/2 regular M&Ms.  Ghirardelli chips are the best!!  Sometimes I use their caramel chips but they are hard to find.

  9. Absolutely,splendid!! These monster cookies will delight any cookie monster! On a 1-10 scale I would rate them a 19!!! Thank you,thank you for posting such a wonderful recipe.

  10. These are by far the BEST monster cookies I have ever made! Wherever I bring them people always ask me for the recipe! It never fails me, they stay so soft for so long. Thank you Sally for this amazing recipe! I have some baking in the oven right now, my girls always ask me to make these

  11. Wondered what I am doing wrong with this recipe. Love the taste but have made them twice, froze them and both times they crumbled into nothing after defrosting. Any suggestions???

  12. These are good cookies, but they are not traditional monster cookies….first thing I noticed was the flour, and no corn syrup. They are simple to make, but should be called something else.

  13. Your recent coffee break post inspired me to make these cookies again. They turned out amazing! Biggest challenge was to not eat all of the yummy dough before even chilling it.
    Since M&Ms are too sweet for my taste, I replaced them with hazel nuts (the only adjustment I made to your receipe). This will be an all time favorite now 🙂 Thank you!

  14. Hi Sally!Love your blog ! I love to bake !will be making these tomorrow for a couple of businesses ! Excited to try them! Looks Delicious!THANKS !Cindy

  15. Yes, absolutely! Roll the dough into balls and freeze them. Bake frozen cookie dough balls for an extra minute, no need to thaw. Enjoy 🙂

1 6 7 8


  1. Love this recipe! The cookies came out beautifully at high altitude (elevation of 8,000ft) without any alterations and we’ve made them multiple times.


Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

With kitchen-tested quality recipes and step-by-step tutorials, my goal is to give you the confidence to bake and cook from scratch.

Recipes You’ll Love



Sally's Baking Challenge

Join the community on the 1st of every month as we tackle a new challenge recipe.

View More

Sally's Cookie Palooza

A tradition since 2013, every December we countdown to Christmas with 10 new cookie recipes in a row!

View More

Sally's Pie Week

The first week of every November is all about Thanksgiving Pies.

View More

My Cookbooks

About Sally

Welcome to my Kitchen!

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