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: 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.



  1. Jen on August 3, 2017 at 3:37 pm

    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. Amanda on August 22, 2017 at 5:48 pm

    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.

    • Sally on August 23, 2017 at 10:55 am

      Yep– I do not suggest natural style PBs in my cookie recipes.

  3. Cheryl Barrios on August 25, 2017 at 11:35 am

    Do these freeze well? I make cookies ahead of time for the holidays and freeze them.

    • Sally on August 25, 2017 at 12:13 pm

      Yes! You can freeze them or just freeze the cookie dough balls and bake them that way 🙂

  4. Jessy on September 7, 2017 at 12:22 pm

    These are so delicious!!!  Amazing and SO EASY, so glad I found your site  🙂

    • Sally on September 7, 2017 at 1:17 pm

      Yay!! Welcome, Jessy 🙂

  5. Courtney on September 26, 2017 at 4:01 pm

    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!!

  6. Michael kain on October 5, 2017 at 12:12 pm

    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.

    • Sally on October 5, 2017 at 12:25 pm

      So happy these are a hit in your house! Salted caramel chips are amazing!!!

  7. Dee on October 27, 2017 at 8:13 pm

    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!

    • Sally on October 28, 2017 at 8:31 am

      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. 🙂

  8. Jen on November 17, 2017 at 7:34 pm

    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.

  9. Lori on December 12, 2017 at 4:49 pm

    Can you make these as a bar cookie?

    • Sally on December 12, 2017 at 8:41 pm

      Definitely. I’d use a 9-inch square baking pan.

  10. Jen on December 18, 2017 at 3:41 pm

    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! 

  11. Melissa on December 19, 2017 at 8:12 am

    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.

  12. E on May 15, 2018 at 11:14 am

    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.

    • Sally on May 15, 2018 at 1:33 pm


  13. Breanna on June 25, 2018 at 2:39 pm

    How many cookies does this recipe make?

    • Sally on June 25, 2018 at 4:22 pm

      About 2.5 dozen 🙂

  14. Dawn on July 2, 2018 at 10:08 pm

    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.

  15. Neta on July 10, 2018 at 1:34 pm

    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

    • Sally on July 11, 2018 at 12:26 pm

      You are welcome, Neta! I’m thrilled that these are such a hit!

  16. Susan on July 31, 2018 at 6:30 pm

    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???

  17. Linda Crosby on August 18, 2018 at 4:22 pm

    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.



Leave a Comment


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.

Top 5 Recipes

Recipes You'll Love




Cookie Palooza

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

View More...


Baking Challenge

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

View More...


Pie Week

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

View More...

My Cookbooks