This classic flourless Monster Cookies recipe has been in my family for more than 25 years and still bakes up the softest, chewiest cookies I’ve ever made. Packed with oats, peanut butter, chocolate chips, and M&M’s, they’re naturally gluten-free and always a crowd favorite.
I originally shared this recipe in 2008, and it quickly became one of the most-loved cookie recipes on Just a Taste.
Chocolatey, chewy, peanut buttery goodness. There’s no better way to describe this tried and tested family recipe for Monster Cookies.
My mom got this recipe from a friend more than 25 years ago, and it’d be impossible to count just how many dozens of Monster Cookies have been baked and enjoyed since that glorious recipe exchange.
These cookies became a staple of mine when I was in college and grad school, and to this day, I’m remembered for their impossibly chewy and soft texture, and of course their unbeatable taste.
My husband jokes that these are a healthy dessert, courtesy of the lack of flour and addition of oats and peanut butter. While “health food” may be a stretch, you can guarantee they are a crowd-friendly dessert. (But if you are looking for a healthy sweet, don’t miss my famous 5-Minute Frozen Yogurt!)
My kids love these cookies 365 days a year, but come October, I add creepy candy eyes to transform them into the ultimate Halloween treat.
And if peanut butter, chocolate chips, oats and M&M’s are your thing, this monster cookie recipe is about to become your all-time favorite.
- Sugars: You’ll need both granulated and light brown sugar. Using a mix gives these monster cookies their perfect chewy yet slightly crisp texture.
- Butter: Start with room-temperature butter so it creams properly with the sugars. If you forget to take it out of the fridge (hi, been there), here’s my trick to soften butter quickly. Use salted or unsalted; just omit the added salt if you go with salted.
- Eggs: Since this is a flourless cookie, they’re essential for structure, richness, and that soft, tender interior.
- Peanut butter: Both smooth and chunky peanut butter will work, but I love the added crunch that chunky offers.
- Vanilla extract: A tablespoon might seem like a lot, but it rounds out all the flavors.
- Baking soda: Since there’s no flour, baking soda helps keep the cookies soft instead of dense.
- Oats: The oats replace the flour in this recipe and give monster cookies their signature chewy bite. Old-fashioned oats will give you a chewier, heartier cookie, while quick oats create a slightly softer, more uniform texture. Use whichever you have on hand!
- Chocolate chips and M&Ms: Mini or regular-sized both work. I’ve tested these with every M&M color and chip size over the past 20+ years, and the rule is simple: use whatever you’ve got! And if you want a festive spin, check out my Christmas monster cookies made with holiday M&M’s and a splash less vanilla for the ultimate December treat.
See the recipe card for full information on ingredients and quantities.
Monster cookies come together in minutes, in just one bowl. No stand mixer? No problem! I made these cookies dozens of times all through college sans mixer. (Consider the stirring your workout for the day.)
You’ll start by creaming the butter, sugar and brown sugar until light and fluffy. Next, add the eggs one at a time, then mix in the peanut butter, vanilla, baking soda and salt. Stir in the oats, then fold in the mini chocolate chips and M&M’s. The dough will be thick, sticky and scoopable.
Scoop 2–3 tablespoon mounds of dough, space them out on a lined baking sheet, and bake at 350°F just until the edges are set. That’s it!
3 Success Tips
- Use a processed peanut butter like Jif or Skippy. While I’m all about natural peanut butter for everyday eating, in baking it behaves very differently. Just like when making peanut butter blossoms or peanut butter chocolate chip cookies, a processed peanut butter is non-negotiable if you want thick, chewy cookies every time. Natural peanut butter separates, which can lead to greasy, flat, unevenly baked cookies.
- Underbake them slightly for soft, chewy centers. The best way to guarantee your cookies are chewy and not too crispy is to underbake them slightly. I recommend the same thing when making my chewy chocolate chip cookies or M&M cookies. If your cookies are coming out dry or crumbly, you likely baked them too long.
- Let the cookies rest on the cookie sheet. Because this recipe has no flour, the structure comes from the eggs, oats, and peanut butter. Letting the cookies cool on the baking sheet for 5–10 minutes helps them set without overbaking.
Making these in October? Add candy eyes as soon as the cookies come out of the oven to turn them into the cutest (and creepiest!) monster cookies.
Storage and Freezing Instructions
Store the cookies in an airtight container at room temperature for up to 5 days.
- To freeze baked monster cookies: Let the cookies cool completely, then freeze in a single layer until solid. Transfer to a freezer-safe bag or container and freeze for up to 3 months. Thaw at room temperature. They keep their texture beautifully.
- To freeze the dough (my preferred method): Scoop the dough into portions, freeze on a baking sheet until firm, then transfer to a zip-top freezer bag. Freeze for up to 3 months. Bake straight from frozen at 325°F, adding about 5 extra minutes to the bake time. They’ll bake more evenly and stay thicker this way.
Ingredients
- 1 cup sugar
- 1 cup packed light brown sugar
- 1/2 cup unsalted butter, at room temperature
- 3 large eggs
- 1 1/2 cups peanut butter (smooth or chunky)
- 1 Tablespoon vanilla extract
- 2 teaspoons baking soda
- 1/2 teaspoon salt
- 4 1/2 cups oats (Old Fashioned or Quick)
- 1 cup mini M&Ms
- 1 cup mini-chocolate chips
- Candy eyes (optional)
Instructions
- Pre-heat the oven to 350°F. Line two baking sheet with parchment paper or Silpat baking mats.
- In the bowl of a stand mixer fitted with the paddle attachment, cream together the sugar, brown sugar and butter until light and fluffy.
- Beat in the eggs, one at a time, and then beat in the peanut butter, vanilla, baking soda and salt until well combined.
- Add the the oats and mix until combined, then add the mini M&Ms and mini-chocolate chips.
- Scoop 2-to 3-tablespoon mounds of the dough onto the prepared baking sheets, spacing the mounds at least 2 inches apart.
- Bake the cookies for 12-15 minutes then remove them from the oven and allow them to cool for 5 minutes on the baking sheets before transferring them to a rack to cool completely. (See Kelly’s Note.)
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Kelly’s Notes
- For best results, use a processed peanut butter like Jif or Skippy. Natural peanut butter separates and can cause the cookies to bake up greasy and flat.
- Chocolate chips & M&M’s: Mini or regular-sized both work. Use the same total amount, regardless of size.
- The best way to guarantee your cookies are chewy and not too crispy is to underbake them slightly then remove them from the oven and allow them to cool for 5 to 10 minutes on the baking sheets.
- Store fully cooled cookies in an airtight container at room temperature for up to 5 days. They’ll stay soft and chewy.
- Freezing baked cookies: Freeze fully cooled cookies in an airtight container or zip-top bag for up to 3 months. Thaw at room temp before serving.
- Freezing cookie dough: Scoop the dough into balls, freeze on a baking sheet until solid, then transfer to a freezer bag. Freeze for up to 3 months. Bake from frozen at 325°F, adding 3–5 minutes as needed.
- If you’re using the candy eyes, add them to the cookies immediately after you remove them from the oven.
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Recipe by Kelly Senyei of Just a Taste. Please do not reprint this recipe without my permission. If you'd like to feature this recipe on your site, please rewrite the method of preparation and link to this post as the original source.
Literally amazing!
So glad you enjoyed the recipe, Elyse!
Not a comment but a question. Is there a smaller conversion? I find the batch is closer to 4 dozen im making many different kinds for holiday can I just half this recipe the ×1 and get the same great cookies?
Hi Anthony! You can definitely halve all ingredients and follow the same directions :)