Peanut Butter Oatmeal Cookies
by Sommer Collier — on Nov 17, 2025 I combined three of my favorite classic cookie recipes to make the thickest, chewiest, and most scrumptious peanut butter oatmeal cookies. Best of all, they’re loaded with chocolate chips and M&M candies for a fun and decadent treat to satisfy your inner cookie monster!
While I usually lean more savory than sweet, I absolutely cannot resist a crisp, chewy, and chocolatey cookie. I know you know what I’m talking about. These peanut butter oatmeal cookies, AKA cookies, are the ones I make most at home when I want to give in to the temptation… It’s basically the lovechild of my family’s favorite cookies. The base starts with my best oatmeal raisin cookies recipe for a soft, yet rustic oat texture. Then a touch of my world-famous(ish) peanut butter cookie recipe is added in, along with chocolate chip cookies for extra richness. These bakery-style beauties have a chewy, thick, nutty oat cookie base studded with M&Ms and melty chocolate chips. I bake up a batch in less than 20 minutes, and they’re gone just as fast!
Table of Contents
Sommer’s Recipe Highlights
Taste and Texture Wonderland – The texture of these cookies is incredible. They’re super soft and chewy, with bits of toothsome oats and a crispy exterior. The M&M’s add a nice textural note as well, with the slightly crunchy candy coating in contrast to melty chocolate chips.
Cookie for all Occasions – I’ve made peanut butter oatmeal monster cookies for afternoon snacks, potlucks, PTA meetings, and bake sales back in the day. But usually I make them on weekends to have a ‘lil treat at the ready throughout the week.
Make Them Your Way – This is a cookie recipe everyone loves, and it’s easy to adjust for gluten-free because it has so little flour to begin with. You won’t notice a textural difference at all! You can also swap out candies and chips to fit whatever taste you’re craving!
Key Ingredients and Tips
- Rolled oats – Don’t mess with this because yes, you need to use rolled oats for the best texture. Quick oats become too soft and steel-cut don’t get soft enough.
- Eggs – Let the eggs come to room temperature before making the cookie dough. Cold eggs take longer to bake, and can mess up the cook time and texture.
- Vanilla extract – I always use top-quality vanilla in my bakes. It has a more pure and less bitter taste, and is so worth the price.
- Butter – I use unsalted butter so I can control the amount of salt in the cookies. This again should be warmed to room temperature so it’s easy to beat into the other ingredients.
- Peanut butter – You can use your choice of crunchy or creamy peanut butter to make the oatmeal cookies. I typically use creamy peanut butter, as I think the chocolate candies have the perfect light crunch on their own.
- Sugars – A combination of brown sugar and cane sugar makes the cookies sweet but with a mellow, deep flavor, and also creates the perfect crispy-chewy textural contrast.
- M&Ms and chocolate chips – These indulgent goodies are what turn regular peanut butter and oatmeal cookies into full monster cookies.
How to Make
Find the full ingredient proportions, detailed instructions, storage tips, and a video tutorial in the printable form at the bottom of the post.
Prep – Preheat the oven to 350 degrees F and line 2-3 baking sheets with parchment paper. Add oats to a bowl along with the eggs, vanilla, and water. Give this a good stir so the oats are completely saturated, and set aside.
Beat – Use a large standing mixer or a large bowl with an electric hand mixer to combine the butter, peanut butter, and sugars until all are smooth and fluffy. I scrape the sides of the bowl down with a rubber spatula about halfway through mixing to make sure every bit of butter and sugar are evenly beaten together.
Mix – Then I set the mixer to low and add the remaining dry ingredients, followed by the oat mixture. The M&Ms and chocolate chips get stirred in last. I do this by hand with a spatula to keep the candies from breaking apart in the dough and avoid over-mixing.
Scoop and Roll – That kind of says it all… I use a big 3-tablespoon cookie scoop and roll the dough into even-sized balls. Place them on the baking sheets, but make sure they’re not too close together. These chunky cookies spread out and get pretty big!
Bake – In the oven, they go for about 15 minutes. You know cookies are done baking when the edges are set and crisp all the way around. They might look slightly underdone, but trust me, the cookies will continue cooking and firm up once you pull them out of the oven and leave them to cool. Don’t over-bake them! Unless you’re a fan of crunchy cookies, then go for it.
Expert Tip
I never add all of the candies to the dough upfront. M&Ms will melt a bit when baked, which doesn’t change the taste, but the color does smear. Instead, I set aside 1/3 cup of the candies, then press them on top of the rolled balls of cookie dough so they are pretty once baked. Because shouldn’t treats look as good as they taste? I think so!
Recipe Variations
- Gluten-free – Swap all-purpose flour for your favorite 1:1 GF baking flour. As I mentioned, there isn’t very much flour in this recipe anyway, so the cookie texture is still fabulous.
- Candies – I’m using good ‘ol fashioned plain M&Ms here. But you can change things up with different candies! Make the recipe with peanut butter, dark chocolate, caramel, or whatever M&Ms you like.
- Chocolate chips – Same thing here, use whatever baking chips you want. Dark chocolate chips, white chocolate chips, and peanut butter chips are some fun options!
Whoa, can you imagine a peanut butter and oatmeal cookie with peanut butter M&Ms and peanut butter baking chips? Definitely let me know in the comments if you give it a try!
Frequently Asked Questions
Quick oats are processed to be thinner and lighter, which makes them great for cooking quickly on the stovetop. Overcooked quick oats become super soft, like a porridge. Rolled oats are left thicker, so they can cook longer without getting mushy, making them ideal for baking!
You sure can, and it does not end well… Trust me. The cookie dough needs to be fully combined, with no eggy-ness or flour streaks. But if you work it too much, the dough will be flat and unpleasantly crunchy.
Absolutely! As-is, this recipe makes 55 cookies, which is a lot. I sometimes halve the ingredients to make only about two dozen cookies.
Storage Notes
The best way to store homemade cookies is in an airtight container at room temperature. They’ll keep well for several days, allegedly. They never make it that long in my house.
Monster cookies are great to freeze, too! Place them all together in a plastic ziploc freezer bag. As a tip, I suggest placing a piece of wax paper between each layer of cookies to prevent them from sticking together. They’ll freeze well for up to 2 months, then just thaw on the counter for 15 minutes or so to soften them back to room temp.
More Cookie Recipes You Might Like
Peanut Butter Oatmeal Cookies
Video
Ingredients
- 5 ½ cups rolled oats (gluten free)
- 5 large eggs
- ¼ cup water
- 1 tablespoon vanilla extract
- 1 cup unsalted butter, softened (2 sticks)
- 1 ¾ cups peanut butter, crunchy or creamy
- 1 ½ cups granulated sugar
- 1 ½ cups light brown sugar, packed
- ½ cup all-purpose flour (or GF baking flour)
- 1 tablespoon baking powder
- 1 teaspoon salt
- 12 ounce semi-sweet chocolate chips
- 12 ounce M&Ms
Instructions
- Preheat the oven to 350 degrees F. Line several baking sheets with parchment paper and set aside.
- In a large bowl, measure out the oats. Then crack the eggs into the oats and add the water and vanilla. Stir to coat, allowing the liquid to saturate the oats.
- In the bowl of an electric stand mixer, add the butter. Beat 1 minute to soften. Then add in the peanut butter, and both sugars. Beat on high for 3-5 minutes to break down the sugar crystals.
- Scrape the bowl with a spatula, and beat again to incorporate.
- Turn the mixer on low and mix in the flour, baking powder, and salt. Once fully mixed in, start adding in the oat mixture.
- Scrape the bowl again, then turn the mixer on low and mix in the chocolate chips. Finally, mix the M&Ms into the dough with the spatula. *I like to reserve a handful of M&Ms to press into the tops, so the cookies are pretty.
- Use a large 3-tablespoon cookie scoop to portion the cookie dough onto the prepared baking sheets. Space the cookies 2 inches apart.
- Bake for 15-17 minutes per batch, until the edges are just barely golden brown, and the centers still look slightly underbaked. Cool for 5 minutes on the baking sheets before moving.
These cookies are absolute perfection – crisp on the outside, chewy inside, and packed with chocolate! My family devoured the whole batch.