Cookie bars

These Monster Cookie Bars are a variation of a monster cookie bar that’s been in my family for as long as I can remember. With a buttery oatmeal crumble, a soft & creamy peanut buttery filling and plenty of M&M’s, these bars will be gone in an instant!

Monster cookies. They’re like the cookie you make when you can’t decide if you want a chocolate chip cookie or an oatmeal cookie or something with peanut butter. A monster cookie combines M&M’s with chocolate chips, peanut butter and oatmeal….all packed into one glorious cookie. I’m pretty sure they named them “monster” cookie, because the bigger the better, right?!

A good monster cookie (or monster cookie bar) will be soft, chewy, peanut buttery and full of chocolatey goodness. But I’ve had monster cookies that just don’t quite cut it. They’re dry and crumbly. Or hard. Or don’t have enough chocolate chips and M&M’s (what a doozy).

When I’m in the mood for a monster cookie, I immediately think of my mom’s monster cookie bars. They have all the components of a monster cookie but in cookie bar form. Oh! And most importantly, they have the addition of a soft, gooey, peanut buttery middle layer. So, what are you waiting for?! Preheat that oven to 375F and let’s get rollin’!

In case you’re more of a visual learner (join the club!), here’s how the layers work!

Are Monster Cookie Bars easy to make?

YES. 100% yes. This is one I’d feel confident even handing over to my hubby to make �� Actually he’s pretty good in the kitchen, but even a beginner can whip these up! As much as I love cookies, I dislike the time it takes to scoop the cookies out, switch out pans in the oven, scoop them to the cooling rack, and repeat a gazillion times.

You’ll make an oatmeal crumble mixture and press most of it into a pan and bake. Then you’ll top it with a creamy peanut buttery mixture, sprinkle with chocolate chips, M&M’s, and the remaining oatmeal mixture and finish baking. Are you drooling yet?!

Steps to make Monster Cookie Bars

1. Preheat oven to 375°F.


2. Combine the oatmeal, brown sugar, soda, flour and salt; stir in the melted butter until combined.


3. Press all but 1 1/2 cups of the oatmeal mixture into a greased 9×13 pan (saving the remaining 1 1/2 cups for later).


4. Bake for 12 minutes.


5. Stir together the sweetened condensed milk and peanut butter; spread over the baked oatmeal layer.


6. Sprinkle M&M’s and chocolate chips on top.


7. Sprinkle the remaining oatmeal mixture on top and press down gently.


8. Bake for 20 minutes or until golden brown.

How do you store Monster Cookie Bars?

I recommend letting them cool on the counter before cutting. Store them in an airtight container at room temperature for up to 5 days or in the freezer for up to 2 months. When you take them from the freezer, simply let them come to room temperature on the counter! Or, let’s be honest…. I’d never be able to wait for a treat to thaw. Toss a bar in the microwave for 10-15 seconds and enjoy!!

Some of my other favorite cookie bar recipes include…

Butterscotch Brickle Bars – Buttery shortbread crust with a butterscotch pecan topping!
Oh Henry Bars – Chewy oatmeal base topped with a combo of chocolate and peanut butter!
Raspberry Bars – Rich, buttery crust, a flavorful raspberry filling and a drizzle of icing on top!