Peanut Butter Cup Surprise Monster Cookies

stack of peanut butter cup monster cookies on a white plate

Welcome to recipe #6 in my Christmas cookie palooza. And let me tell ya, it’s a winner. Do I say that about every recipe I share? Dessert lover problems.

overhead image of monster cookies with one cookie broken in half showing a peanut butter cup inside

There are 2 reasons why I made today’s cookies:

1) My first post on Sally’s Baking Addiction includes peanut butter, so it seems only natural to celebrate my blog birthday with peanut butter the best flavor on earth.

2) Last year during my Christmas Cookie Palooza, I shared an absolutely ridiculous peanut butter stuffed cookie. Let’s make it a yearly tradition.

So there is always a reason to make peanut butter cup surprise monster cookies. I bet if you think real hard, you can find an excuse to make them too. Like, it being Thursday. And/or that you love M&Ms. And that peanut butter cups rule the world. And/or because your love for peanut butter cups runs deep.

Reese's peanut butter cups

The concept for these stuffed cookies is simple. Start by making the easiest peanut butter cookie dough. Guess what? There’s no mixer required. This oatmeal cookie dough can be mixed by hand. And it gets better: there is no dough chilling required either. The quicker you begin, the quicker you’ll be eating these.

This peanut butter cookie dough is a little different from my original monster cookies. It’s actually quite similar to my peanut butter cup oatmeal cookies. Instead of two sugars, however, I use all brown sugar in this particular cookie recipe. The reason for that? Softer oatmeal cookies. Brown sugar makes cookies extra soft because of all its moisture. Without the presence of granulated sugar, I noticed that these cookies didn’t spread as much. That’s one of granulated sugar’s jobs– to induce cookie spreading. I didn’t notice much of a taste difference using all brown sugar, but that’s only because there is so much peanut butter flavor. It overpowers everything else! A good thing, for sure.

To this peanut butter oatmeal cookie dough, add mini M&Ms. Regular size M&Ms are cool too. But I like the mini ones because you get more M&Ms in each monster bite. Traditional monster cookies include chocolate chips, but I didn’t add any to this recipe since there’s a chocolate treat hidden inside. Speaking of..

2 images of monster cookie dough with a peanut butter cup on top and monster cookie dough surrounding peanut butter cups on a silpat baking mat

Stuffing them is easy. Grab some cookie dough, pat it down to flatten, place peanut butter cup on top, mold more cookie dough on top and around peanut butter cup.

Like I mention above, the cookie dough only spreads slightly in the oven. So, I suggest gently pressing down on the stuffed cookie dough balls to slightly flatten them (as best you can!) before baking. This gives them a little spreading “push.”

overhead image of monster cookies with one cookie broken in half showing a peanut butter cup inside

At first sight, they look like regular oatmeal M&M cookies… BUT it’s when you take that first bite when you notice all the peanut butter flavor and the hidden peanut butter cup surprise inside. These chewy, soft, overloaded oatmeal cookies will leave everyone begging for more. If heaven were a cookie, this would be it. ↓

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overhead image of monster cookies with one cookie broken in half showing a peanut butter cup inside

Peanut Butter Cup Surprise Monster Cookies

  • Author: Sally
  • Prep Time: 25 minutes
  • Cook Time: 12 minutes
  • Total Time: 1 hour
  • Yield: 18 cookies
  • Category: Cookies
  • Method: Baking
  • Cuisine: American


Peanut butter monster cookies with a Reese’s peanut butter cup inside!!


  • 3/4 cup (94g) all-purpose flour (spoon & leveled)
  • 1/4 teaspoon salt
  • 1/2 teaspoon baking soda
  • 1/2 cup (115g) unsalted butter, melted
  • 1 cup (200g) packed light or dark brown sugar
  • 1 large egg, at room temperature
  • 1/2 cup (125g) creamy peanut butter (not natural style)
  • 2 teaspoons pure vanilla extract
  • 2 cups (160g) quick oats*
  • 1 and 1/4 cups mini or regular size M&Ms
  • 18 Reese’s miniature peanut butter cups, unwrapped


  1. Preheat oven to 350°F (177°C). Line 2 large baking sheets with parchment paper or silicone baking mats. (Always recommended for cookies.) Set aside.
  2. Toss the flour, salt, and baking soda together in a large bowl. Set aside.
  3. In a medium bowl, whisk the melted butter and brown sugar together until no brown sugar lumps remain. Whisk in the egg, then the peanut butter until combined. Finally, whisk in the vanilla. Pour the wet ingredients into the dry ingredients and mix together with a large spoon or rubber spatula. The dough will be very soft and slick. Fold in the oats and the M&Ms. Allow the cookie dough to sit for 15 minutes– the oats will absorb some moisture, making the dough easier to work with.
  4. You can use the photos above as visuals for this step. Take 1 Tablespoon of dough and slightly flatten out on the prepared baking sheet. Stick a peanut butter cup on top, as shown above. Top the peanut butter cup with 1.5 Tablespoons of cookie dough and seal down the sides so that the peanut butter cup is securely stuffed inside. You can pick it up and roll into a smooth ball if needed. Slightly flatten down the top as best you can (it can’t be totally flat because of the peanut butter cup inside). Repeat with the rest of the dough and peanut butter cups.
  5. Bake the cookies for 12-13 minutes. The cookies will look very soft. They will continue to bake on the cookie sheet. Remove from the oven and lightly press down on each cookie to slightly flatten (if they didn’t spread much in the oven). Allow to cool on the cookie sheet for 10 minutes before transferring to a wire rack to cool completely.


  1. Make Ahead Instructions: Cookies stay soft and fresh for 7 days at room temperature. Baked cookies can be frozen up to 3 months. You can freeze cookie dough balls by assembling as directed. Then chill in the refrigerator until firm and ready to pick up (you’re doing this because the cookie dough is so sticky). Once firm, freeze dough balls in ziplock bags. Bake as directed for 1-2 extra minutes, do not thaw.
  2. Oats: I do not recommend using old-fashioned style oats (aka whole oats) in this cookie recipe. They are the large-cut oats. You need quick oats, which are more finely ground (and smaller) whole oats. I often only buy old-fashioned (whole oats) from the store. So for this recipe, I simply pulse whole oats in a food processor a few times to cut them down to “quick oat” size.
  3. Be sure to check out my top 5 cookie baking tips AND these are my 10 must-have cookie baking tools.

Keywords: peanut butter cup stuffed monster cookies, monster cookies


  1. Ramona @ The Merchant Baker says:

    Wow..3 years…time flies! I remember when you were celebrating your first! These cookies look like a hearty bunch of yum!

  2. Amy @ Amy's Healthy Baking says:

    Happy blog birthday SBA!! 🙂 Sally, you’ve come SO far in just 3 short years. From your first blog post until now, your dedication to baking and honoring your grandmother with every cup of flour, tablespoon of peanut butter, and shower of sprinkles really shows. And your bright and beautiful photographs are just the frosting on the cupcakes! Or PB cup in the cookies… Regardless, you’re truly an inspiration and I’m so happy to have “met” you online! And I really want about 6 of these cookies right now. That’s all. 🙂

    1. And I really want to meet in real life and talk about cookies with you all day 🙂 xoxo Amy!

      1. Amy @ Amy's Healthy Baking says:

        I can’t wait for that day to come! Hopefully soon! 🙂

  3. Stephanie @ Girl Versus Dough says:

    Happy blog birthday, Sally! Cookies with peanut butter in them are always a perfect way to celebrate. 🙂 I actually just told my mom we probably won’t be baking any cookies together this year, but I might have to change that now that I’ve laid on these bebes!

    1. Stephanie @ Girl Versus Dough says:

      That would be, “laid eyes on.” Oy. 😉

      1. Hahahahahahahahahaha I love you Stephanie.

  4. jenna @ just j.faye says:

    These look so SO good! Congrats on the three year anniversary! I love your blog 🙂

  5. Happy Birthday, SBA!!!
    These cookies look awesome. So excited to make these, not just because they look amazing, but also the whole batch would be just for me. Strangely, my in-laws are not a huge fan of peanut butter in cookies. I know! How is it even possible, right??

    1. Hahahaha I know people who don’t like PB in cookies too. I don’t understand (??) but to each his own!!

  6. Amy @ Thoroughly Nourished Life says:

    I freakin’ love these cookies too Sally!
    Happy 3 year blog birthday! The internet is a much more sparkly, sprinkly, peanut buttery, and awesome place because you are in it!
    So grateful that you share your life, your baking talents, and pictures of the gorgeous Jude with us every week 🙂
    You keep baking, we’ll keep loving!
    🙂 Amy

    1. Thanks Amy, you’re the sweetest. =)

  7. Anna (Hidden Ponies) says:

    Happy 3 years, Sally!! Your Grandma would be so very honoured and impressed by what she inspired 🙂

  8. Stacey @ Bake.Eat.Repeat. says:

    Happy blog birthday Sally! These cookies look absolutely insane! So much chocolate and peanut butter, it doesn’t get much better than that!

  9. I made these last night!! Oh my, they were incredible!! A keeper for the recipe drawer!! Very easy to make too!!

    1. Excellent! Thanks Chelsey.

  10. Abbie @ Needs Salt says:

    Ahh, these cookies! They look pretty much perfect to me. (: And I can’t believe you’ve been blogging for 3 years!! Golly, has time flown or what. Keep up the awesome cookie awesomeness, girl!

  11. Sometimes you need a cookie that is unpretentious, not uptight, and would NEVER EVER be paired with wine. This cookie is perfect for those moments.

  12. Jessica @ Jessica in the Kitchen says:

    Wowza these are some loaded cookies! They are so thick and pretty and love that there is no dough chilling time. What’s even more amazing? Happy 3rd Anniversary for your blog!! I wish you many more great years blogging.

  13. What a coincidence! I just made your biscoff oatmeal white chocolate cookies tonight, and I can see that this recipe base is similar. Can’t wait to try it – it is super easy and I love no mixing/chilling for weeknight baking. Btw, the biscoff cookies are amazing!!!

  14. Hi Sally!
    I was just wondering if it would be possible to freeze this cookie dough to bake at a later date, and how you would go about doing that?
    Thanks so much, these look amazing!

    1. Absolutely! You may freeze cookie dough balls by assembling as directed. Then chill in the refrigerator until firm and ready to pick up (you’re doing this because the cookie dough is so sticky). Once firm, freeze dough balls in ziplock bags. Bake as directed (do not thaw) for 1-2 extra minutes.

  15. I just made these tonight, and my taste testers and I thought they were amazing!! I doubled the recipe to bring to my boyfriend’s family for the holidays and I think they will love them 🙂 Thanks for the recipe!

  16. Hello, Sally!!
    I really want to try this recipe, but I was wondering if there’s anything that can replace the oats…
    Thank you in advance and I hope you have a nice day!

    1. Hi Sarah! I suggest making this peanut butter cup stuffed cookie recipe and adding M&Ms:

  17. Just made this cookies – SO good!! However, I did find that chilling for 30 mins made the dough wayyy easier to work with. My dough was very very sticky and my first batch spread more than I liked. Chilling the dough, and not pressing the cookies down, completely solved this problem!

    Thanks for another amazing recipe, Sally!!

  18. I’ve made these cookies 3 times now and the only problem I’ve encountered is that I found the dough to be runny.  I’ve followed the recipe as is so not sure where the issue is.  BUT, this will not stop me at all from making these cookies.  They’re absolutely delicious and always a huge hit.  The last time I made them I actually crushed the mini cups and added them to the dough (because I just needed more chocolate peanut butter in every bite)!!  I’m so glad that I found you’re site.  Looking forward to making more of your yummy goodies!  

  19. The last time I made these, my family that doesn’t normally eat too many sweets ate a whole bunch. They were a total success. My sister asked me to make them for her party coming up… I’ll be doubling the recipe so that we have extras. =] So delicious!

  20. I think these cookies are delicious! I followed the gram measurements, and didn’t even bother measuring with cups. I love it when I can just weigh something. I also love that I didn’t need to use my stand mixer. I actually made these cookies twice today. When my family discovered how good they were, I made a second batch to share with the kids I teach at my church. I chilled the dough the first time for about 30 minutes, and the second time for an hour. It made the dough a little easier to handle, but it’s still a little tricky to mold and shape around the PB cup. I kind of pressed the dough balls firmly together in between my hands until it was sealed all the way around… if that makes any sense. I DO think chilled dough helped make the dough less sticky. These are definitely a keeper. They’re yummy. They’re a good thickness. And I love that they have that hidden surprise inside. Thanks for the recipe, Sally!

  21. Oh yum I love peanut butter and chocolate really want to try these!

  22. I can’t wait to try these, we are a peanut butter loving family. I was wondering, why is it suggested NOT to use “natural” peanut butter? Skippy’s Natural Creamy (“no need to stir”) is a staple in our house. Would that work?

    1. Hi Lori! Natural style PB is typically very oily and would result in overly crumbly cookies. But Skippy’s natural no-stir variety would be great here.

  23. Hi, I see that you can freeze the cookie dough, but wondering if you can freeze the baked cookies? If so – for how long? Thanks!!

    1. Hi Terri! Yes, you can freeze the baked cookies. See my make ahead tip.

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