Monster Cookie Bars
Monster cookies baked into bar cookies – peanut butter dough loaded with oats, chocolate chips and M&M’s.
Have you ever tried monster cookies?
If you’re not familiar with them, the cookies are traditionally made with a peanut butter dough and then loaded up with oats, chocolate chips and M&M candies. While I love cookies, sometimes bars get overlooked, so this weekend I baked up a whole pan of monster cookie bars! They were a big hit on Halloween while we were waiting to get Joseph into his costume, and still popular after Sunday dinner yesterday.
There are a million and one recipes floating around the internet for monster cookies and I’ve tried a few different versions, but this one is my most recent favorite.
The dough is soft, the peanut butter flavor comes through but isn’t overpowering, the oats are abundant, and there is a ton of chocolate thanks to the chips and M&M’s. You could totally play around with this recipe and switch up the add-ins, but I love the classic combination of chocolate chips and M&M’s – you just can’t go wrong!
I think it goes without saying that these would be super popular with kids, but I can vouch for the fact that they’re incredibly popular with adults, too!
Four years ago: Leftover Halloween Candy Bark
Monster Cookie Bars
Ingredients
- ½ cup (113.5 g) unsalted butter, at room temperature
- 1 cup (220 g) light brown sugar
- ½ cup (129 g) creamy peanut butter
- 1 egg
- 2 teaspoons vanilla extract
- ¾ cup (93.75 g) all-purpose flour
- 1 teaspoon baking soda
- 1 teaspoon cornstarch
- ¼ teaspoon (0.25 teaspoon) baking powder
- ¼ teaspoon (0.25 teaspoon) salt
- 1½ cups (121.5 g) old-fashioned oats
- 1 cup (180 g) semisweet chocolate chips
- 1 cup (236.59 g) M&M's + additional for top of bars
Instructions
- Preheat the oven to 350 degrees F. Grease a 9x13-inch paking pan and line with parchment paper so that it hangs over two sides.
- In a small bowl, whisk together the flour, baking soda, cornstarch, baking powder and salt.
- In a large bowl, cream together the butter, brown sugar, and peanut butter on medium speed until light and fluffy, about 3 minutes. Add the egg and vanilla, scraping down the sides of the bowl as needed. Reduce the mixer speed to low and slowly add the flour mixture to the wet ingredients and mix until just combined. Using a rubber spatula, stir in the oats, chocolate chips and M&M's by hand.
- Turn the dough out into the prepared baking sheet and press/spread into an even layer. Press additional M&M's onto the top of the dough. Bake for 15 to 17 minutes, until the edges are set and lightly browned and the top still looks slightly undercooked. Remove from the oven and cool completely before cutting into bars. The bars should be stored in an airtight container at room temperature for up to 4 days.
Notes
Did you make this recipe?
Leave a review below, then snap a picture and tag @thebrowneyedbaker on Instagram so I can see it!
I love this recipe and have made them several times. Simple and always a hit! I use different types of chips and mini m&ms.
I do have to say though that I love your site but it’s becoming increasingly difficult to get to the recipe without running into the ads and videos. ☹️ I had to close out and start over twice because I got into a video loop.
The recipe says to keep at room temperature in an airtight container. Could you freeze these?
Hi Sandy, Yes absolutely!
Delicious, better the next day once the oats softened (the oats near the center of the bars were still a bit chewy the first day). Very cookie like bars, perfect peanut butter flavor.
Can the oats be substituted for flour?
Hi Rosalinda, I have not tried to do that, so I’m not sure how the batter would be affected.
I made these last weekend, and they are excellent. Just a hint of peanut butter really adds a nice dimension to these bars, and of course, all the chocolate chips and M&Ms make for an excellent cookie! On my way to make another batch now!
Awesome cookie bars!! All love them!
Hi Michelle! I just wanted to let you know that I made these bars this past weekend for a party, and they were delicious! Everyone loved them, especially the kids of course! And they were so much easier than cookies- since it’s just one pan in the oven and done! I’ll definitely make them again, maybe trying some with Reeces Pieces instead of m&ms sometime! :)
Have a wonderful Christmas!
These were absolutely amazing!! The taste and texture was perfect. Love how the oats kept them from being too rich. They made a ton and lasted for almost a week. Need to bring dessert this weekend and I’m going to make these again!!
Thanks for posting this recipe! They are cooling in the pan as I type. When I took them out after 17 minutes, they were still very, very wet. Everything shifted with a slight tilt of the pan. It took a total of 25 minutes to get the finished product looking as you described it. They smell delicious; my kids will be happy to have a yummy treat after school.
Can I use quick cooking oats instead of the old fashioned oats? Your recipe looks better then any other I seen on here.They would be good for my diet with all the oats they would fill me up after only one and keep me full awhile. Thanks for such a good looking recipe.
I wouldn’t recommend substituting quick oats, as they will absorb the moisture in the dough differently than the traditional oats.
Just wondering why you would need to grease the pan AND use parchment paper? Thanks.
Hi Kim, I’ve found that it helps the parchment stick and stay in place.
These are the most moist cookie bars I’ve ever had really good everyone loved them. The one thing I am going to try next time is using mini m&ms and mini chocolate chips. When they were cut the would crumble on the part with an m&m or chocolate chip. Will definitely be making many more times!
Yummy this has me getting hungry look at these!!
xoxoBella | http://xoxobella.com
still waiting for your mom’ bracciole recipe.
Can you omit the peanut butter without any problems?
Hi Dale, You can’t, as it’s a primary part of the base dough.
i have made these in cookie form for years. they are always a big hit. will now try in bar form. thanks
Love that you made these into bar cookies. It’s funny, I always think I don’t want a cookie that has m and m’s in it because I think the crispy candy shell will bother me in the cookie. So, I usually take a piece of my kids’ cookies, then find myself negotiating for more pieces :) These look yummy!
In this case “a picture is worth a thousand words” could easily be changed to 1 word – DELICIOUS comes to mind instantly. These look fantastic. Definitely adding them to my wanting-to-make list. By the way, most of the recipes on my list come from here. Thanks for adding to it, Michelle :)
Yes yes yes! Can’t wait to try this recipe! I’m adding these to my baking list for the holidays.
A monster cookie recipe on Cookie Monster Day- too clever BEB!!
Yay, now all the leftover Halloween candy can live a delicious second life in these chewy pieces of deliciousness! So yum-EH!
Wow, these look fabulous!! I’m going to have to give these bad boys a try.
Katie xoxo
If I get a plateful of these monster cookies, it will seriously brighten my day up! I mean, who can resist all the peanut butter goodness and those bright M n Ms ! I certainly cannot! love it!