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At first glance, these might look like ordinary oatmeal M&M cookies, but the secret surprise inside makes this dessert a game changer. Peanut butter cup surprise monster cookies are soft and chewy M&M-speckled oatmeal cookies filled with a creamy peanut butter cup.

Peanut butter + oats + M&Ms = monster cookies! But this peanut butter cookie dough is a little different from our original monster cookies. They’re a little closer to these peanut butter cup oatmeal cookies. The difference? For this recipe, we use all brown sugar to keep the cookies extra soft and flavorful.

stack of peanut butter cup monster cookies on a white plate

Tell Me About these Peanut Butter Cup Surprise Monster Cookies

  • Flavor: Peanut butter is front and center. You’ll love all the peanut butter flavor paired with chocolate from both the peanut butter cup and M&Ms. 
  • Texture: Thanks to the brown sugar, these cookies stay thick, soft, and extra chewy. Quick oats are responsible for the uniform texture. Make sure to use quick oats, NOT old-fashioned oats. Quick oats are smaller than old-fashioned oats and more finely ground. Tip: If you only have old-fashioned oats, just pulse them in your food processor a few times so they’re smaller. While regular M&M’s certainly work, we prefer the mini ones because you get more M&Ms in each monster bite.
  • Ease: Start by making the easiest peanut butter cookie dough. Guess what? There’s no mixer required. And it gets better: there’s no dough chilling required either. The quicker you begin, the quicker you’ll be eating these peanut butter cup monster cookies.
  • Time: No dough chilling makes this recipe one of the quickest and easiest cookies on our website. If you want cookies in a hurry, here are a few more time-saving cookie recipes that don’t require chilling. Snickerdoodles and shortbread cookies are two favorites!
overhead image of monster cookies with one cookie broken in half showing a peanut butter cup inside

Reese's peanut butter cups

How to Add the Peanut Butter Cup Surprise

At first it might seem intimidating to sandwich a peanut butter cup inside a cookie, but it’s super easy. Once you try it, you’ll be adding surprises to all your cookies, like we did with these salted caramel dark chocolate cookies and Reese’s stuffed peanut butter cookies.

Here’s the scoop. Literally.

  1. Scoop 1 Tablespoon of dough onto your baking sheet. Pat down the dough to flatten.
  2. Press a peanut butter cup into the top of the flattened cookie dough.
  3. Then scoop 1.5 Tablespoons of cookie dough and place on top and around the peanut butter cup. Make sure you seal the edges of the cookie. This will prevent the peanut butter cup from leaking out. 
  4. Since this cookie dough only spreads slightly in the oven, you might need to help it along. Before you start baking, gently press down on the stuffed cookie dough balls to flatten them slightly. This gives them the little spreading “push” they need.
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

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

More Cookie Recipes To Discover

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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 1x
  • 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. Read my tips and tricks on how to freeze cookie dough.
  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

Reader Questions and Reviews

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

  2. 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!

  3. 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!!

  4. 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!

  5. 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!

  6. 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.

  7. 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!!

  8. Is it okay to substitute the m&ms for just regular mini chocolate chips? Very excited to make these today!
    Thank you:)

  9. I love that you don’t have to chill this cookie dough! The cookies are so easy to make.

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