This post may contain affiliate links, view our disclosure policy.

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.

overhead pic of the 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…

A stack of the peanut butter monster cookie bars

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.

Close up shot of the top of the cookie bars

Ingredients Needed

  1. 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.
  2. 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.
  3. Light Brown Sugar
  4. Granulated Sugar
  5. Large Eggs
  6. Vanilla Extract
  7. Old-Fashioned Whole Oats : The whole oats provide tons of hearty texture for the cookie bars and makes them so chewy and soft.
  8. 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.
  9. Baking Soda
  10. Reese’s Pieces : If you can find the mini sized Reese’s Pieces then I definitely recommend using those!
  11. Peanut Butter Chips
Ingredients

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.

process images

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.

process images

Cut into squares using a pizza cutter (makes it so easy!) and enjoy! These can be eaten warm or cooled to room temperature.

Stack of the cookie bars with Reese's pieces.

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.

Overhead pic of the cookie bars with one bar taken out of the pan

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!
Cookie sheet of monster cookie bars with lots of peanut butter.
A stack of the peanut butter monster cookie bars
Together As Family Logo

Triple Peanut Butter Monster Cookie Bars


Course Dessert
Cuisine American
Prep Time 15 minutes
Cook Time 15 minutes
Cooling Time 30 minutes
Total Time 1 hour
Servings 36
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.

Ingredients
  

  • 1/2 cup (1 stick) salted butter softened
  • 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
  • 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

Peanut Butter : Do not use ‘all-natural’ peanut butter or peanut butter with a thick oil layer on top in this recipe. For best results, and texture of cookie bars, use regular classic creamy peanut butter. I have found that the all-natural peanut butter tend to dry out baked goods and make the texture drier. 
I love freezing extra bars because this recipe makes a lot! Wrap one or two bars in plastic wrap, and then place the wrapped bars inside a freezer-safe container or Ziploc bag. Eat them chilled, let them sit at room temperature for a bit, or warm it up in the microwave. 

Nutrition

Calories: 216kcal | Carbohydrates: 26g | Protein: 5g | Fat: 11g | Saturated Fat: 4g | Polyunsaturated Fat: 2g | Monounsaturated Fat: 4g | Trans Fat: 0.1g | Cholesterol: 21mg | Sodium: 120mg | Potassium: 140mg | Fiber: 2g | Sugar: 17g | Vitamin A: 102IU | Calcium: 24mg | Iron: 1mg

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!

 

 

Did you love this recipe?

Make sure to comment below so we can chat about it! Or follow on your favorite social network for even more family recipes.

5 from 3 votes (2 ratings without comment)

Leave a Reply

Your email address will not be published. Required fields are marked *

Recipe Rating




13 Comments

  1. 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!

    1. Together As Family says:

      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!

      1. 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!

        1. Together As Family says:

          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 🙂

  2. Pingback: {no flour!} Cookies n' Cream Oatmeal Cookie Bars - Together as Family
  3. 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

  4. 5 stars
    Everything a good cookie should be! Quick to make, it uses everything you already have on hand, delicious soft and chewy.

    1. Together as Family says:

      Thank you so much! What a kind comment 🥰

  5. 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).

    1. Together as Family says:

      Yeah, one of those things that people always have a different name for 😆 but yes, a baking pan with sides is perfect!

  6. 5 stars for these cookies. They are my families new favorite

  7. Is it possible to make these with all old- fashioned oats instead of mixing the quick cooking oats with it?

    1. Together As Family says:

      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!