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Boooo! Halloween Monster Mash Cookies! Festive, easy, sweet, and gravely spooky! Homemade chocolate chip cookies, made with oats, pretzels pieces, plenty of chocolate chunks, spooky Halloween M&M’s, and crazy candy eyes. There’s nothing not to love about these sweet chocolate cookies with a little salty pretzel crunch. Each bite is slightly crisp on the edges but soft and gooey in the center with melted chocolate throughout.

Ahhh! I am so happy to share these! In all honesty, I’ve wanted to make these fun, super yummy cookies for months. Actually, since almost a year ago when I made my much loved Christmas Monster Cookies. It was then that I knew that Halloween Monster Cookies needed to follow.
I’m not sure which cookie I love more. Both are unique, special, and melt-in-your-mouth delicious.
I know, I’m such a dork, but nonetheless, I just love how fun Halloween can be!
I wanted to share them very early in the Halloween season. My hope is that you can bake them up for all of your Halloween needs. Parties, school functions, and even just as a fun cookie to bake on a random weekday. Whatever you bake them up for, they require almost no effort!

Start off by gathering all of your ingredients. You’ll need the basics: salted butter, dark and light brown sugar, flour, baking powder, baking soda, and salt – the usuals.
You’ll also need the stir-ins, they’re the most important element of these cookies. You’ll need old-fashioned oats, salted pretzel twists, semi-sweet or dark chocolate chunks, and candy eyes. Plus plenty of spooky Halloween M&M’s, which, of course, make these cookies.
Simply mix up the dough, bake each cookie off, and then enjoy!

We love to eat these cookies warm, just out of the oven. They’re just the right type of gooey delicious cookies to pull out, slightly cool, and indulge in.
One thing that’s important to note, is that these cookies do spread, so don’t stress on that. Because of this, they’re meant to have slightly crisp edges and perfectly soft gooey centers, just like in the photos. My favorite type of cookie. Everyone has really been loving these cookies, they’re definitely an Oslo favorite!

If you want a bit of a thicker cookie, simply omit the additional egg yolk and use only two eggs. As a result, this will give you a thicker cookie without as much spreading.
To get the M&M’s to really pop, I like to add in a few just before the cookies finish baking completely. This way each cookie has a bit of the festive M&M’s right on top.
Excited to see you all bake these up this month! What’s incredible about these cookies is just how easy they are. So have fun with them and enjoy every shamefully sinful spooky monster bite!

Looking for other Halloween cookies? Here are my favorites:
“I put a Spell on You” Poison Apple Martini
Black Widow Peanut Butter Bars
Hocus Pocus Spellbook Brownies
BOO! Chocolate Peanut Butter Bars
Milk Chocolate Stuffed Jack-O’-Lantern Cookies
Lastly, if you make these Halloween Monster Mash Cookies, be sure to leave a comment and/or give this recipe a rating! Above all, I love to hear from you guys and always do my best to respond to each and every comment. And of course, if you do make this recipe, don’t forget to tag me on Instagram! Looking through the photos of recipes you all have made is my favorite!
Nutritional information is only an estimate. The accuracy of the nutritional information for any recipe on this site is not guaranteed.

If I don’t have pretzels, what might you sub?
Hey Meghan,
I would just skip them:) I hope this recipe turns out amazing for you, let me know if you have any other questions! xx
These taste fine, but they’re sooo flat and gooey that I just cannot get them to set. They turned out kind of a mess. My oven temp is correct and my leavening agents are fresh. I even tried refrigerating the dough, and that didn’t help. They taste good, but look very messy (which is sorta cute for Halloween, but wouldn’t work any other time!).
Hi there,
Thanks for giving the recipe a try and sharing your feedback! I do note “One thing that’s important to note, is that these cookies do spread, so don’t stress on that. Because of this, they’re meant to have slightly crisp edges and perfectly soft gooey centers, just like in the photos. If you want a bit of a thicker cookie, simply omit the additional egg yolk and use only two eggs. As a result, this will give you a thicker cookie without as much spreading.” I hope this helps for next time! xT
Yummy! Just made a half batch and think they’re to “die” for 😉 cute touch w the eyeballs! My kids can’t wait to have in their lunch tomorrow!
Hey Stacy,
Awe love to hear this!! Thanks for making them and sharing your feedback!! Have a great Thursday! xTieghan
I love how this recipe came together so easily. They taste delicious and so festive for the Halloween season. Another big hit in my house. Thanks, Tieghan!
Hi Julie,
Happy Friday!! I am delighted to hear that this recipe turned out tasty for you, thanks a bunch for giving it a try!
I followed this recipe to a T and my cookies are very dense balls and didn’t flatten. What did I do wrong?
Hi Shona,
Thanks for giving the cookies a try. Were all of your ingredients at room temp? Is it possible you over mix the dough? Have you tried tapping your baking sheet on the counter or gently flattening the dough with your hand? Let me know! xTieghan
Would peanut butter m&ms work in this recipe? Or would that be too many flavors?
Hey Amanda,
Sure, peanut M&M’s would be great! Let me know if you give the cookies a try, I hope you love this recipe! xT
Hello! Can you use instant oats or steel cut oats instead of old fashion oats?
Hi Sherish Ali,
For this recipe, I would recommend sticking with the old fashioned oats! Please let me know if you have any other questions! xTieghan
Can you use gluten free flour in place of the all purpose? Look these but my niece is gluten free. Thank you 🙂
Hey Ashley,
Yes, that will work well for you! I hope you love these cookies, please let me know if you give them a try! xTieghan
Hi
Can I refrigerate the dough a day or two ahead.
Hey Jackie,
Totally, that will work well for you! I hope you love this recipe, please let me know if you give it a try! xT
Just pulled these out of the oven. Wow! Just wow! My husband claims that these are the best cookies he’s had in a long time. I think he was wondering why I bought pretzels today because we’re both not pretzel fans. Now when I told him this was where the pretzels were in, he figured best pretzels he’d ever had!
Hey Teresa,
Happy Wednesday! I am thrilled to hear that this recipe was a winner, thanks a bunch for making it! xT
Hello, I would remove the M&Ms and indulge in eats. Thank you for sharing.
I hope you love the recipe!
Love these – can I omit the oats? thank you!
Hi Lesley,
I’ve not tested this, but if you omit the oats I would add 1/3 cup of flour. Let me know if you give the recipe a try! xTieghan
where did you purchase the eyes?
https://www.wilton.com/candy-eyeballs-with-lashes/191009021.html
The link above opened to Target when I clicked it. Hope that helps!
Hi Lynn,
Here is the link for the eyes, unfortunately they are sold out!
https://shopstyle.it/l/bMsrL
I hope you love the recipe! xx
These look great! I was also wondering about the eyes with eyelashes. I’ve checked Halloween M&Ms and they do not appear to have those.
Hi Vickie,
These are the ones that I used, unfortunately they are all sold out! https://shopstyle.it/l/bMsrL
Please let me know if you have any other questions! xT
Can I use quick oats? I made the mistake of buying them instead of old-fashioned for my granola and would prefer to use them up before buying more… these look amazing! Thanks!
Hi Alix,
So sorry, you will definitely want to use old-fashioned oats for best results with these cookies:) Please let me know if you have any other questions! xx
Thank you for the response – I’ll add them to my list 🙂
Where did you get the eyelash sugar eyes? Did you make them yourself?
I was going to ask this question too. Thanks. Will watch for her answer
Hey Erica,
Here is the link for the exact ones that I used:
https://shopstyle.it/l/bMsrL
Unfortunately, they are totally sold out! Let me know if you have any other questions! xT