Monster Cookies: Best Ever Recipe

If Halloween had a cookie mascot, it would be Monster Cookies. Besides having the name to fit the part (what better time for monsters than Halloween?) Monster Cookies are loaded with chocolate and peanut butter candies, the prize flavors of the trick-or-treat assortment.

Back in the glory days of trick-or-treating, my sisters and I would spread our haul of candy on the carpet before us, sort it into piles based on personal priority, then commence the Great Halloween Candy Swap. Our living room was a mini-incubator for the free market at its finest. While my sisters opted for anything sour or fruity, I was—and still am—all about the chocolate and peanut butter.

I’m a chocolate + peanut butter lover to the core, and I loaded these Monster Cookies with both flavors. For the unfamiliar, a Monster Cookie is a peanut butter oatmeal cookie that is packed with yummy mix-ins, most traditionally M&M candies and chocolate chips. After experimentation, I am pleased to report that I have created the Ultimate Best Ever Blow-Your-Mind Monster Cookies. Pin this recipe now friends—this is the only Monster Cookie recipe you will ever need.

That statement is a total superlative, and I’m standing by it.

Best Ever Monster Cookies

Our Monster Cookies begin with the softest, fluffiest peanut butter oatmeal cookie recipe I have ever created. Honestly, we could leave out all of the mix-ins, and we would still have a fabulous peanut butter oatmeal cookie. This is Halloween, however, candy is a must. Let’s packed our perfect peanut butter-oatmeal base with semi-sweet chocolate chips, dark chocolate M&Ms, and (for even more peanut butter flavor) peanut butter chips. Double the peanut butter, double the chocolate, double the delectability.

Don’t even pretend you are going to eat just one. Monster Cookies are not single-serving territory. I recommend pouring an extra large glass of milk to keep pace, these Monster Cookies are that outstanding. Plus look how little and fun they are! Their cuteness alone is reason enough to go back for more.

As I shared with my Peanut Butter Cake with Chocolate Chips, when it comes to chocolate and peanut butter, I am loud and proud about flavor, and these Monster Cookies are no exception. Though I chose dark chocolate M&Ms, feel free to pick your favorite M&M flavor (or use a mix!)

Monster Cookies are also a tasty vehicle for any extra Halloween candy you have on hand. Try swapping in chopped Reeses, Twix, Hershey bars, or Butterfingers. The amazingly soft and fluffy peanut butter oatmeal Monster Cookie base is a delightful canvas for your candy favorites.

Some of us may be too old to go knocking door to door on Halloween, but that doesn’t mean we shouldn’t treat ourselves. Let’s start with a big batch of softy, chewy Monster Cookies. No tricking here friends—these are the best Monster Cookies I have ever tasted, and I’d bet my entire stash of peanut butter and chocolate that they will be yours too.

My candy is on the line! Give these Monster Cookies a try.

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Monster Cookies

Best Ever Monster Cookie Recipe: Soft, fluffy peanut butter oatmeal cookies loaded with chocolate chips, M&M candies, and peanut butter chips. Feel free to sub in your favorite candy to make them your own and don’t be surprised when they disappear!

Yield: 36-40 small (2-inch) cookies

Prep Time: 20 minutes

Cook Time: 10 minutes

Total Time: 30 minutes


  • 1/2 cup (1 stick) unsalted butter, softened
  • 3/4 cup firmly packed dark brown sugar
  • 1/4 cup granulated sugar
  • 1/2 cup creamy peanut butter
  • 1 large egg, at room temperature
  • 1 teaspoon pure vanilla extract
  • 1/2 teaspoon baking soda
  • 1/4 teaspoon kosher salt
  • 1 cup white whole wheat flour or whole wheat pastry flour
  • 1 cup old fashioned rolled oats
  • 3/4 cup dark chocolate M&Ms
  • 1/2 cup semi-sweet or dark chocolate chips
  • 1/2 cup peanut butter chips


  1. In a large mixing bowl, cream butter, brown sugar, and granulated sugar until light and fluffy, about 3 minutes. Add peanut butter and beat until fluffy again, about 2 minutes, scraping down the bowl as needed. Beat in egg and vanilla until combined.
  2. Sprinkle the baking soda and salt over the top. With the mixer on low, gradually add the flour, mixing just until the flour disappears. Slowly beat in the oats. By hand, stir in the M&Ms, chocolate chips, and peanut butter chips. If time allows, chill dough for 30 minutes or overnight.
  3. When ready to bake, place racks in the upper and lower thirds of the oven and preheat the oven to 350 degrees F. Line two cookie sheets with parchment paper or a silpat mat. Drop cookies onto the sheets by rounded tablespoons. Bake for 10 minutes in the upper and lower thirds of the oven, until lightly golden brown (cookies may appear underdone). Let rest on cookie sheet for 5 minutes, then transfer to a wire rack to cool. Serve with a big glass of cold milk.

Store leftover Monster Cookies in an airtight container for up to 1 week.

All images and text ©/Well Plated.

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About Erin Clarke

I’m fearlessly dedicated to making healthy food taste incredible. Wearer of plaid, travel enthusiast, and firmly convinced that sweets and veggies both deserve a place at the table. MORE ABOUT ERIN…


  1. Monster cookies are SO good! Love that you snuck whole wheat flour in here too.

  2. Monster cookies are always so good. I can’t meant to try these!!

  3. I have never made monster cookies but they always look so incredible! I am pinning this recipe for sure!

  4. haha my sister and I did the exact same thing as kids. She liked nerds and sour patch kids and I was always about the chocolate/peanut butter combo. And we also clearly blasted halloween music while doing this – monster mash anyone??

    I love these cookies – I haven’t made monster cookies in far far too long.

  5. Me amnd my mom have said many times that monster cookies truly are the best cookies. Ever. I think it is the oats and MnMs. I’ve never made them with pb chips and will definitely throw those in next time. So true about single serving … haha, there is no such thing!

  6. Well, you had me at chocolate and peanut butter! These look amazing, and since I haven’t made monster cookies in ages, they are totally going on the “to-make” list.

  7. Okay, I have a confession… I never really jumped on the M&M’s-in-a-cookie band wagon… but I think that is all about to change. I was all about the peanut butter and chocolate as a kid, too (and still am!), and these cookies sound over-the-top in the best possible way. And they are so cute and tiny! I would eat a dozen without thinking twice. Nom!

  8. consuelohoneyandfigs Reply

    I love how fun these look and I’m definitely a sucker for the pb + chocolate + oats combo, but it’s super dangerous for me to have m&m’s around, because I always eat them all before putting them in the cookies oooOOooops. They’re so yummy, it’s impossible to stop at one ;)

  9. I love a good monster cookie! I was, and still am, only in the Halloween spirit for the pb & chocolate candy (Reese’s were like hitting the jackpot, let’s face it), but now that I am old enough to buy my own and bake them into cookies, that Halloween happiness can last year round.

  10. Monster cookies kind of own my heart! You’re sending some my way right?!

  11. I am not too crazy about sweet and sour variety either. If we were sisters, it would not have ended well :P

  12. These look awesome! Monster cookies are one of my favorites. In my experience they’re really good for shipping during the holiday season too since they are sturdy and stay nice and chewy for a few days!

  13. I love monster cookies! I actually can’t believe I don’t even have a recipe on my blog for it. They’re definitely one of my absolute favorite cookies that remind me of childhood! I remember they were all I wanted to make. Yours looks fabulous!

  14. Halloween is made for monster cookies! I like to throw every candy I can into this dough and call it supper.

  15. Who doesn’t love M&Ms? These monster cookies look awesome!

  16. I LOVE monster cookies! They are so easy, fun and adaptable. These are perfect for Halloween!!!

  17. Well I know what I’m doing with our left over Halloween candy!! These are wonderful Erin! Pinning for Friday!

  18. What a great way to use up Halloween candy! Plus I’m a sucker for anything with peanut butter chips – I love those little things! These look so good

  19. I love Monster cookies. The texture, the oats, the M&Ms! Yes! :)

  20. They look oh so good. I’m sure my kids would love me forever if I made them these. Well, maybe not forever but at least the rest of the day. ;)

  21. Monster Cookies are one of my all-time favorite desserts! I’ve never made them with peanut butter chips so I can’t wait to try your version!

  22. Oh. My. Yum! These cookies look delicious! Fingers crossed the trick-or-treaters leave me enough M&M’s so I can make these this weekend.

    And thanks for commenting on my blog. Now I’ve found yours and I love it! Adding you to my reader. Can’t wait to see what you make next : )

  23. Monster cookies are my absolute favorite cookies! Can’t wait to try your version!

    • Thanks Jessica!!!! I was obviously way excited about them, lol. If you give them a try, I’d love to hear what you think! If they are your fave, you’ll be a great judge :)

  24. Oh my goodness, look at these gorgeous little colorful gems! You’ve totally taken me back with these cookies, Erin. They’re dangerously easy, so I’ve gotta give them a go!

  25. These monster cookies look perfect, I love how fun they are. Definitely on the list of sweets to make!

  26. I NEVER make cookies but I think I’ll have to try these. I adore PB&C.

    Would it be inappropriate to steal my kid’s Halloween candy to make these? Or worse, hypocritical if I were to forbid candy but let him eat candy in a cookie? Ah, the great dilemmas in parenting…

    • Sarah, if you adore PB&C, these cookies have your name written all over them! Mega parental conflict. I think if you steal the candy, give your kiddos a cookie or two, then hide the rest for your personal midnight snack needs, everyone will walk away happy ;-)

  27. Ohhh how I wish I could go trick-or-treating tomorrow just to get candy for these cookies!! Guess I’ll be one of the crazies raiding the discounted Halloween candy!

  28. Hi Erin! These cookies are loaded with all sorts of goodness! I would have a hard time not eating the entire batch! Thank you for sharing them with us!

  29. OMG! These are packed with goods. So delicious

  30. I have such great memories of candy sorting and swapping- maybe the best part of Halloween! These cookies look like perfection :-)

  31. I’ve never heard of a monster cookie. Clearly, I had a huge deficit in my early development (I need to remedy that now by eating as many of these cookies as possible, just so… well, I get a good idea as to how wonderful they are). One problem: peanut butter chips don’t exist in Australia *waaaah!*. Should I just omit them altogether or should I add something else? xx

    • Peanut butter chip tragedy! You need to come to the states and stock up ASAP Laura ;-) Feel free to swap out the PB chips for whatever mix ins you like: more chocolate chips, butterscotch chips, chopped candy bars, or if you want to add more PB flavor, chopped peanuts would be delicious too. That’s the beauty of monster cookies: they transform to fit your pantry!

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