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.

cookie palooza logo image

Not only are we in the middle of a Christmas cookie celebration, today we’re also celebrating Sally’s Baking Addiction’s 3rd birthday. I can’t believe that I’ve been at this for three years! In the past three years I: got engaged, quit my job, started a business, moved 3 times (remember the flood?), wrote a cookbook, met readers, and got married. I started my blog two weeks after my grandmother passed away. She’s to whom my cookbook is dedicated and the main source of my inspiration.

And to all of you? I just want to say hey, thanks for reading my blog. =)

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

There are three 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.

3) My peanut-butter-oatmeal-cookie-loving friend just turned 30 and I made desserts for her surprise party last weekend. We celebrated at a bar nearby with friends and family, lots of good food, wine, balloons, and a sugar overload. I made two batches of these, one pan of these, and a batch of today’s monster cookies. The cookies were the first dessert to disappear.

So there is always a reason (or three!!) 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 (95g) 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. Averie @ Averie Cooks says:

    Love that this is a no mixer and no chilling kind of recipe! You don’t find that very often with cookies! And all that texture from the oats, the pb cups, the M&Ms, so good!

  2. Jessica @ Citrus Blossom Bliss says:

    Congrats on your 3 years! That’s quite an accomplishment, and what better way to celebrate than with these beautiful/sinful monster cookies!!

  3. Congrats on three amazing years, Sally! I dunno what I’d do without your blog as inspiration 🙂

  4. Happy blog birthday, Sally! Wishing you many more blog years to come – always love your posts 🙂

    These cookies are phenomenal – YUM.

  5. Kerry @ Kerry Cooks says:

    Happy Birthday to SBA and congratulations Sally! You have an awesome site 🙂

  6. Looks to die for…..literally 🙂 Happy 3th Birthday SBA… all the best for the future xxx

  7. Happy blogiversary! You’re super amazing and super lucky and super everything!
    How do these not spread without chilling? It’s a cookie miracle! As is the inner PB cup. You could make giant ones with the bigger-sized cups if you wanted to get really crazy, huh?
    Right up my alley, Sally! Oops, accidental rhyme. My bad.

    1. Oats supremely help with the no-spreading miracle. Plus, the dough is so thick. Thick dough = less spread. Kevin suggested the regular size Reese’s to make giant cookies too. I like your styles.

  8. Happy blogiversary, Sally! That’s amazing it’s been three years…and you share amazing recipe after recipe! These cookies are INSANE, and I really, REALLY want to try them! 🙂

  9. Happy birthday SBA! What an accomplishment Sally girl! Cheers with cookies!

  10. Nurfatma Perveen says:

    Happy Birthday SBA!!!!!!

  11. Laura @ Laura's Culinary Adventures says:

    Happy blog birthday! These look decadent 🙂

  12. Kaitlyn @ Birch Tree Baking says:

    These just moved to the top of the holiday baking list! Anything with peanut butter and chocolate and I’m in! Happy 3rd blog birthday!

  13. Happy Blog Birthday! You’ve done a fantastic blog these past three years and I can’t wait to see where the years will take you!
    Now, if you’ll excuse me, I have some monster cookies to go bake 🙂

  14. Ceara @ Ceara's Kitchen says:

    Happy 3rd year blog-aversary, Sally!! Peanut Butter sounds like the perfect way to celebrate! They cookies look like they have such an awesome texture! Yum! 😀

  15. That last wrap-up sentence was on point. Also, these cookies make me want to die (in a good way). I’m a sucker for peanut butter oatmeal. Happy 30th, Katy!!

  16. Natalie @ Never Serious Blog says:

    Oatmeal and peanut butter, so yum!

  17. These look amazing! I just got home from the gym and these are all I can think about haha. Thanks so much for the oats tip, I pretty only buy whole oats too and had never thought to pulse them in a blender to substitute!

  18. I wanted a picture of the gooey center. Where’s the cookie in half?

  19. Austria Azaceta says:

    Hi Sally,
    I usually like to wait till i try a recipe to leave a comment but I just wanted to say Happy Blog Birthday/Anniversary!!! I absolutely LOVE to bake & therefore LOVE your blog! I’ve learned so many useful tips & tricks, & your recipes NEVER disappoint! Keep up the good work & thank you, thank you, thank you…. 🙂
    Now, these cookies need to be made asap! I just made a batch of your flourless oatmeal peanut butter ones & the candy cane fudge to send as a gift to a GF friend. I know she will love them… But i must stop ‘talking’ now & go out & get reese’s cups & mini m&m’s…..

    1. Thank you Austria! I appreciate it! What nice homemade gifts for your friend.

  20. Happy 3rd birthday, Sally’s Baking Addiction!
    I was wondering if you have any similar recipes without nuts?
    My baking friend/partner is allergic but we really want to make cookies like these. I know you’re kind of obsessed with peanut butter, but . . .

    1. How about making these:

      There is not peanut butter cup inside, but still M&Ms and oats.

  21. Trisha Franklin says:

    Happy Birthday Sally’s Baking Addiction! Love these cookies, something different for a monster cookie. And, like everyone else has said, NO spreading. Those are the best kinds of cookies. Did you pack your brown sugar for this recipe? I know I’ve seen you use it both ways. I typically pack when in doubt, but wanted to make sure these come out as perfect as yours look.

    1. Trisha, I always always pack brown sugar. All of my recipes that call for brown sugar (unless otherwise noted with “loosely packed”), pack it!

      1. Trisha @ Two Food Lovers says:

        Thanks, Sally!

  22. I’m going to a cookie party this weekend and everybody is bringing homemade cookies to share. I’m fresh out of ideas. What should I bring?

  23. Happy anniversary to you and your blog! I am so glad I found you – your recipes are always spot on!

    I wasn’t PLANNING on peanut butter cookies this month but these look KILLER! (If they are anything like your classic peanut butter cookies…oh my….I might faint!) 🙂

    1. You will loooooooove these Christine!

  24. Eve @ Baking the Day says:

    Happy Birthday SBA!!! Your blog is so amazing, keep up the great work! I am in love with these cookies, peanut butter and m&ms are perfect for a worthy celebration.

  25. Happy Birthday to SBA and Katy! I would love to be a good friend of yours; although, I’m pretty sure I would have to wear stretchy pants for the rest of my life (which doesn’t seem too bad haha!). I love baked goods with a surprise in the center. I always think cupcakes with fillings are definitely winners over the unstuffed variety. Go big or go home, right?!

    1. Stretchy pants and filled cupcakes are the best. =)

  26. Happy 3rd anniversary! I, for one, am so very glad you decided to start a blog with all of your delicious creations. You have helped me gain confidence in my baking abilities and for that, I thank you. 🙂

  27. Jennifer @ Show Me the Yummy says:

    Congratulations on SBA’s 3rd birthday! That’s so exciting 🙂 Also, there’s no better surprise than a Reese’s stuffed into a cookie! 😉

  28. Kayle (The Cooking Actress) says:

    HAPPY BLOGAVERSARYYYY!!! You’re so amazing!

    These cookies are giant and epic and full of YUM! LOVE that you stuffed them with pb cups!

  29. Michelle @ Modern Acupuncture says:

    Aw, Happy Blog Birthday, Sally!! Your site is amazing and always brings a little joy to my day. I hope Sally’s Baking Addiction has at least another 30 birthdays to come!

  30. Cate @ Chez CateyLou says:

    Happy Birthday to SBA! What an amazing three years it has been. I love your blog so much! What a perfect way to celebrate – Peanut Butter must be involved for a celebration 🙂

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