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Triple Peanut Butter Monster Cookie Bars are loaded with peanut butter, peanut butter chips, mini reese’s pieces, and oatmeal! This recipe makes an entire cookie sheet of cookie bars & they freeze perfectly.
Triple Peanut Butter Monster Cookie Bars (Sheet Pan Cookie Bars)
If you’ve followed this blog for awhile then you know that we are obsessed with all things peanut butter and monster cookie. Some of our other favorites are these No Flour Monster Cookie Bars and Monster Cookie Energy Balls. It was only a matter of time until I made an all peanut butter version of our favorite. Because let’s be real, triple the peanut butter is always better.
These cookie bars are one of THE BEST things I have eaten. The last time I said that was when I posted these Triple Peanut Butter Monster Cookies. You see the peanut butter pattern here…
These cookie bars have no flour in them so they’re a great treat for those who are sensitive to gluten; just make sure to use 100% gluten-free oats in the recipe!
They are loaded with peanut buttery goodness in three ways; creamy peanut butter, peanut butter chips, and mini reese’s pieces. They also freeze perfectly. I cut the bars into squares (use a pizza cutter, so easy!) and then put a couple into sandwich bags and place in the freezer. They are actually really good straight from the freezer, or leave them on the counter for a few minutes, or warm in the microwave for 10-15 seconds.
Ingredients Needed
- Butter : I prefer using salted butter in this recipe because there is no additional salt called for, and I just prefer using salted butter for all my baking. You can use unsalted butter but you may want to add about 1/4 teaspoon of sea salt or kosher salt in with the dry ingredients.
- Creamy Peanut Butter : It’s best to use normal, classic creamy peanut butter and nothing that is labeled as ‘all-natural’ or anything with that thick layer of oil on top. I love the Peter Pan brand of peanut butter.
- Light Brown Sugar
- Granulated Sugar
- Large Eggs
- Vanilla Extract
- Old-Fashioned Whole Oats : The whole oats provide tons of hearty texture for the cookie bars and makes them so chewy and soft.
- Quick Oats : These are the quick cook oats that are usually labeled as ‘quick oats’ or ‘1-minute oats’. They have a finer texture and do a great job at soaking up the moisture in the bars and binding the bars together. The quick oats combined with the whole oats is a delicious combination in these cookie bars.
- Baking Soda
- Reese’s Pieces : If you can find the mini sized Reese’s Pieces then I definitely recommend using those!
- Peanut Butter Chips
How To Make No Flour Peanut Butter Monster Cookie Bars (Printable Recipe Card)
Heat the oven to 350 degrees F. Prepare a rimmed cookie sheet (12″x18″) and spray it with cooking spray or line it with parchment paper.
In a large mixing bowl using an electric mixer, or use a stand mixer with the paddle attachment, beat the butter, peanut butter, light brown sugar, and granulated sugar on medium speed until it’s combined well, creamy, and fluffy looking. About 2-3 minutes.
Add in the eggs and vanilla extract and beat on medium speed until combined.
Add in the old-fashioned oats, quick oats, and baking soda. Beat until everything is thoroughly mixed together.
Add in the Reese’s Pieces and peanut butter chips, and beat until they’re combined well in the cookie dough.
Dump the monster cookie bar dough onto the prepared cookie sheet and spread it out with your clean hands, wooden spoon, or spatula.
Bake for 16-20 minutes. The edges should be lightly golden brown while the middle should still look somewhat pale and slightly underdone.
Remove the cookie sheet from the oven and let it cool, at room temperature, for 30 minutes to 1 hour so the bars can cool down, firm up, and continue cooking slightly.
Cut into squares using a pizza cutter (makes it so easy!) and enjoy! These can be eaten warm or cooled to room temperature.
How To Store Leftovers
Store the cookie bars inside an airtight container, or Ziploc bag, at room temperature for up to 3-4 days.
You can also store them inside the refrigerator for up to 7 days; reheat the cookie bar in the microwave for a few seconds or let it sit out at room temperature for a few minutes. The bars are actually good chilled, so either way is yummy.
To freeze the bars, wrap each bar individually in plastic wrap and then place the wrapped bars inside a freezer-safe Ziploc bag or container. Freeze for up to 2 months. Eat the bars chilled, let them sit at room temperature for a bit, warm it up in the microwave, or put it in a lunch box and it will be thawed by lunchtime.
Recipe Tips
- Use regular creamy peanut butter for the best results. I don’t recommend using anything labeled as ‘all-natural’, ‘no-stir’, or any peanut butter with that thick oil layer on top. Those peanut butters tend to dry out baked goods and make them for dense. I love the Peter Pan brand of peanut butter, but Skippy or Jif are good also.
- If the cookie bar dough is too sticky and it’s hard to spread here are a few tips; spray your clean hands with cooking spray to help, use the butter wrap to spread the dough out, or use the back of a plastic spoon (the plastic tends to make spreading stickier things easier).
- Reserve some of the peanut butter chips and Reese’s Pieces to sprinkle over top the bars before baking. This will make them look really pretty!
More Must-Try Monster Cookie Inspired Recipes
- Giant Monster Cookie
- Triple Peanut Butter Monster Cookies
- The Best Monster Cookies
- No Flour Monster Cookies
- Monster Cookie Dough Cheeseball Dip
- Monster Cookie Brownies
- Reese’s Stuffed Monster Cookies
- Monster Cookie Dough Bars
- Monster Cookie Magic Bars
Triple Peanut Butter Monster Cookie Bars
Ingredients
- 1/2 cup (1 stick) salted butter softened
- 1½ cups creamy peanut butter
- 1 cup light brown sugar
- 1 cup granulated sugar
- 3 large eggs
- 1 tablespoon vanilla extract
- 3 cups old-fashioned oats
- 1½ cups quick oats
- 1 teaspoon baking soda
- 1 bag (9.9 oz) Reese's Pieces (or Mini Reese's Pieces)
- 1 cup peanut butter chips
Instructions
- Heat the oven to 350° F. Prepare a cookie sheet (12" x 18") and spray it with cooking spray or line with parchment paper. Set aside. *I use a pre-cut piece of parchment paper because I think parchment paper helps the bars cook more evenly and prevents the bottoms from over browning.
- In a large mixing bowl using an electric mixer, or use a stand mixer with the paddle attachment, beat the butter, peanut butter, light brown sugar, and granulated sugar on medium speed until it's combined well, creamy, and fluffy looking. About 2-3 minutes. *It's important to beat at least 2 minutes. You want the creamed mixture to be very pale in color and fluffy looking.1/2 cup (1 stick) salted butter, 1½ cups creamy peanut butter, 1 cup light brown sugar, 1 cup granulated sugar
- Add in the eggs and vanilla extract and beat on medium speed until combined.3 large eggs, 1 tablespoon vanilla extract
- Add in the old-fashioned oats, quick oats, and baking soda. Beat until everything is thoroughly mixed together.3 cups old-fashioned oats, 1½ cups quick oats, 1 teaspoon baking soda
- Add in the Reese's Pieces and peanut butter chips, and beat until they're combined well in the cookie dough. *If wanted, reserve some of each to press on top of the bars before baking. This is optional. Just makes them look pretty.1 bag (9.9 oz) Reese's Pieces, 1 cup peanut butter chips
- Dump the monster cookie bar dough onto the prepared cookie sheet and spread it out with your clean hands, wooden spoon, or spatula.*Gently press the reserved Reese's Pieces and peanut butter chips onto the top of the bars, if using.
- Bake for 16-20 minutes. The edges should be lightly golden brown while the middle should still look somewhat pale and slightly underdone. *It's important to not overbake the bars. They will continue cooking and setting as they cool. I always bake for the minimum time.
- Remove the cookie sheet from the oven and let it cool, at room temperature, for 30 minutes to 1 hour so the bars can cool down, firm up, and continue cooking slightly.
- Cut into squares using a pizza cutter (makes it so easy) and enjoy! These can be eaten warm or cooled to room temperature.
Notes
Nutrition
Did You Make This Recipe?
I’d love to see it! You can share it with me on @togetherasfamilyblog and follow on Pinterest @together-as-family-blog-recipes or Facebook @togetherasfamilyblog for more!
Tried these today and I loved them!! My family did, too. My 11 yr old son said- “These are a 10 out of 10, I could not stop eating them!” I used all quick oats, 3/4 cup of each sugar, chunky peanut butter and chocolate mixed with peanut butter chips. Then I put mini Reese’s cups on top. Just used what I had around ?. These are very versatile and a large recipe. Easy to make, too!! Thank you so much!
I love your variation! My kids can’t stop eating them either 🙂 Thanks so much, Anne, for coming back and commenting and for your kind words!
I know I’m crazy to comment again, but my husband loved these so much he made them yesterday. It was simple for him and they must have been delicious because the whole pan is already gone!
Hey! I love hearing from readers who have tried recipes…… It makes my day, so thank you! I’ll be honest, I make a lot of things but these monster cookie bars are by far, the one thing that we make over and over again. We love them too, and I am so glad you guys love them! Have a good day 🙂
Hi! Do you think it would work to sub. mini Reese’s Cups instead of the Mini Reese’s Pieces ? Cause i’m not really a fan of the Reese’s Pieces…..But I love chopped up Reese’s Peanut Butter Cups in my Oatmeal Chocolate Chip Cookies so I thought they would taste good in these bars
Everything a good cookie should be! Quick to make, it uses everything you already have on hand, delicious soft and chewy.
Thank you so much! What a kind comment 🥰
I was confused by the instructions because it says to put on a cookie sheet, but in looking at the pictures, I’m assuming that was a typo and it should be in a baking pan (with sides not a baking sheet).
Yeah, one of those things that people always have a different name for 😆 but yes, a baking pan with sides is perfect!
5 stars for these cookies. They are my families new favorite
Is it possible to make these with all old- fashioned oats instead of mixing the quick cooking oats with it?
I have had readers comment and say they have done all old-fashioned oats with success, so yes you can. I prefer the mix of both kinds. I think using all quick oats would make the bars too dry, so if you only want to use one kind of oats then the old-fashioned would be the ones to use. Hope that helps. I will update the recipe with those notes, thank you!