Soft and Chewy Monster Cookies
These monster cookies are made with my favorite peanut butter oatmeal cookie dough, and there are M&M’s and chocolate chips in every single bite. There’s no dough chilling required and you can use any mix-ins you like to customize your cookies!
*Originally published in July 2019. Post and pictures updated September 2026. *
After baking countless batches of these monster cookies over the years, I decided it was time to share the updated recipe I’ve been loving lately.
The peanut butter oatmeal cookie dough base is the same classic recipe that I first shared back in 2019, but this new and improved version calls for more chocolate chips (because you can never have too much chocolate!).
This is a no-frills cookie recipe that goes straight from the mixing bowl to the oven. The cookie dough doesn’t have to be chilled before being rolled into balls and baked, and you can use pretty much any combination of mix-ins you like.
It’s really the perfect “anytime” cookie recipe that’s ready in about 30 to 45 minutes. I love this easy recipe so much that I even included a variation of it in my cookbook!
Recipe Video
Ingredient Notes & Substitutions
Peanut Butter
Avoid natural peanut butter because it tends to separate and creates greasy cookies. A no-stir variety like Jif or Skippy is best.
Oats
I prefer using rolled oats to give these cookies a chewier texture. I’ve also tested this recipe with quick oats and they work great, so feel free to use whichever one you have on hand!
Mix-Ins
I used chocolate chips and M&M’s, but you can use your favorite baking chips, chopped pretzels, chopped nuts, etc. Mini M&M’s will work too!
Tips For Making These Cookies
- Mix the butter and sugar together long enough. Give it a good 1 to 2 minutes to properly cream together the sugar and butter. This incorporates the perfect amount of air into the butter so your cookies turn out soft and chewy, not cakey.
- Stop and scrape down the sides of the bowl often. You want all of the ingredients to be evenly incorporated into the dough.
- Measure your flour correctly. If you scoop the flour straight out of the bag with the measuring cup, you’re likely going to end up with too much and dry/crumbly cookies. Instead, you want to spoon it into the measuring cup, then level it off with the back of a butter knife. If you’re new to baking I have a full blog post explaining more about how to measure flour correctly.
- Use a cookie scoop. This will keep all of your cookies uniform in size. I love to use this 1.5-tablespoon cookie scoop for these monster cookies.
- Don’t over bake the cookies! My cookies usually take about 10 to 12 minutes. You’ll know they’re done when the tops are just set (no longer doughy) and the edges start to lightly brown. It’s also best to use a light colored baking sheet because it will bake the cookies more evenly. If you use a darker baking sheet, you may need to reduce the baking time slightly.
Can I Leave Out The Peanut Butter?
You can’t leave it out of this recipe without making adjustments to some of the other ingredients. If you want to make these cookies nut-free, you can replace the peanut butter with an equal amount of SunButter or Wowbutter.
Or you could use my oatmeal chocolate chip cookie recipe and just replace half of the chocolate chips with M&M’s.
Can I Bake This Recipe Into Bars?
Yes! This should be enough cookie dough for a 9-inch square pan, just bake until the top is set and lightly golden brown. If you’d prefer to make a larger batch in a 9×13 pan, you can use my monster cookie bar recipe instead.
Make a batch of these monster cookies this weekend and watch them disappear. I know you’re going to love them!
If you try this recipe, don’t forget to leave a comment and star rating below to tell me how your cookies turned out. Happy Baking!
Monster Cookie Recipe
Ingredients
- 1 cup all-purpose flour spooned & leveled (125 grams)
- 1 ¼ cups old-fashioned rolled oats (125 grams)
- ½ teaspoon baking soda
- ¼ teaspoon salt
- ½ cup unsalted butter softened (113 grams; 1 stick)
- ¾ cup packed light brown sugar (150 grams)
- ¼ cup granulated sugar (50 grams)
- ½ cup creamy peanut butter (125 grams; I recommend Jif or Skippy avoid natural pb)
- 1 large egg at room temperature
- 1 teaspoon pure vanilla extract
- ¾ cup M&M's (155 grams)
- ¾ cup semi-sweet chocolate chips (135 grams)
Instructions
- Preheat the oven to 350°F (177°C). Line two to three large baking sheets with parchment paper or silicone baking mats and set aside.
- In a large mixing bowl, whisk together the flour, old-fashioned rolled oats, baking soda, and salt. Set aside.1 cup all-purpose flour,1 ¼ cups old-fashioned rolled oats,½ teaspoon baking soda,¼ teaspoon salt
- In the bowl of a stand mixer fitted with the paddle attachment, or in a large mixing bowl using a handheld mixer, beat the butter, brown sugar, and granulated sugar together for about 1 to 2 minutes or until well combined. Mix in the peanut butter, egg, and vanilla extract until fully combined, making sure to stop and scrape down the sides of the bowl as needed.½ cup unsalted butter,¾ cup packed light brown sugar,¼ cup granulated sugar,½ cup creamy peanut butter,1 large egg,1 teaspoon pure vanilla extract
- Add the dry ingredients and mix until just combined. Add the M&M’s and chocolate chips and gently fold them into the cookie dough (you can also mix them in on low speed with your mixer).¾ cup M&M's,¾ cup semi-sweet chocolate chips
- Using a 1 ½ tablespoon cookie scoop, scoop the cookie dough onto the prepared baking sheets, making sure to leave a little room between each one.
- Bake in separate batches for 10 to 12 minutes or until the tops of the cookies are set and the edges are just lightly browned. Remove from the oven and allow to cool on the baking sheet for 5 to 10 minutes, then transfer to a wire rack to cool completely.
Fab recipe, can’t wait to try it! How big would you say each cookie is, either weight wise as dough or size when baked? If I wanted to make less quantity but a bigger size, how would I adjust time and temp? My family loves the big NYC style cookies, thank you 🙂
With a 1.5 tablespoon cookie scoop, they’re probably about 3-inches in diameter. For larger cookies, I would scoop about 1/3 cup of dough for each one. You can keep the oven temperature the same and increase the baking time slightly (maybe 14 to 17 minutes total).
How many cookies does this recipe make?
It makes 32 cookies. The servings are listed right above the ingredients in the recipe card 🙂
This is my go to recipe for these cookies. They are so good
Love these cookies! Recipe turned out great…even with my kids helping 🙂
They were delicious, but I had to add a 1/4 cup of flour more to the batch and when I did they tasted so much better!
they are awesome cookies. first ones to turn out in a long time.
I researched Monster Cookies recipes and decided on yours and so glad I did! I do not like cakey cookies, I like them soft and chewy and these did not disappoint. They are excellent cookies and everyone loved them. Thank you for this recipe.
I normally don’t leave reviews but this recipe was not soft or chewy. It was dry and broke apart. So disappointed because it was a waste of my time and expensive ingredients.
The cookies should not have been dry or falling apart. Did you double check the ingredients and measurements that you used? Specifically the flour, butter, sugar, and peanut butter? Happy to try to help you figure out what happened, but you made a point to leave a fake name and email address, which makes that difficult.
Made your cookies tonight with no edits and they were delicious. Thank you for the recipe.