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    Home » Dessert » Bars

    Monster Cookie Bars Recipe

    Updated: Mar 20, 2024 · by Tonia Larson

    This post may contain affiliate links.

    ↓ JUMP TO RECIPE

    Monster cookie bars are so much easier to make than cookies! This monster cookie bars recipe includes oatmeal, peanut butter, M&M’s and chocolate chips.

    Monster Cookie Bars

    When I get a craving for cookies, I take out the ingredients, mix up the cookie dough (usually a double batch) and start forming the cookies, one cookie sheet at a time.

    But it doesn’t take long before I am sick of making cookies and ready to leave the kitchen with a couple of warm, fresh cookies and a steaming cup of coffee to enjoy while reading a magazine.

    Has this ever happened to you? My solution is to make cookie bars instead. You get the delicious homemade cookies and they are done all in one pan! This past week, I switched up my usual Brown Butter Chocolate Chip Cookie Bars for these Monster Cookie Bars.

    Disclaimer: Please note that some of the links in this post are affiliate links. There is no additional cost to you, but I will earn a small commission if you purchase through those links.

    How To Make Monster Cookie Bars

    Chocolate Chip Monster Cookie Bars Ingredients in Mixer

    Start by mixing together the baking soda and water in a small bowl, set aside. In a stand mixer with a large bowl (I used my Kitchen Aid mixer), cream together butter, shortening, peanut butter, and sugars.

    Add the eggs, vanilla, and salt. Mix in the baking soda/water mixture. Add flour, one cup at a time, mixing well after each addition. Add the quick oats, mix well. Stir in M&M’s and chocolate chips.

    Monster cookies bars in pan

    Spread the dough in a greased jelly roll pan measuring about 15×10 or half a sheet pan measuring about 16×12 (I use a Wilton cookie pan with sides.) and bake at 350 degrees for 20-25 minutes, until golden brown.

    Monster Cookie Bars Slices

    Cut into bars. If you are patient, wait for them to cool first, if you love warm, gooey cookies as much as I do, cut a piece as soon as you can!

    Stack of Monster Cookie Bars

    These bars are perfect for serving at a party. Watch them disappear when there is a group of hungry teenagers around! My husband brought this pan of Monster Cookie Bars to work to share with his coworkers and they loved them.

    Monster Cookie Bars | thegunnysack.com

    Monster Cookie Bars Recipe

    Monster cookie bars are so much easier to make than cookies! This monster cookie bars recipe includes oatmeal, peanut butter, M&M's and chocolate chips.
    4.75 from 8 votes
    ↑ Click stars to rate!
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    Prep Time: 15 minutes minutes
    Cook Time: 25 minutes minutes
    Total Time: 40 minutes minutes
    Servings: 48
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    Ingredients

    • 2 teaspoon baking soda
    • 2 teaspoon water
    • ½ cup butter
    • ½ cup shortening
    • 1 cup peanut butter
    • 1 ½ cups brown sugar
    • 1 ½ cups granulated sugar
    • 4 large eggs
    • 2 teaspoon vanilla
    • 2 teaspoon salt
    • 3 cups flour
    • 2 cups quick oats
    • 1 cup M&M's
    • 1 cup semi-sweet chocolate chips

    Instructions

    • Preheat the oven to 350˚F.
    • Start by mixing together the baking soda and water in a small bowl, set aside.
    • In a stand mixer with a large bowl, cream together butter, shortening, peanut butter and sugars.
    • Add the eggs, vanilla and salt.
    • Mix in the baking soda/water mixture.
    • Add flour, one cup at a time, mixing well after each addition.
    • Add the quick oats, mix well.
    • Stir in M&M’s and chocolate chips.
    • Spread the dough in a greased, rimmed half-sheet pan measuring at least 17x12-inches and bake at 350˚F for 20-25 minutes, until golden brown.
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    Nutrition

    Serving: 1slice | Calories: 198kcal | Carbohydrates: 26g | Protein: 3g | Fat: 9g | Saturated Fat: 4g | Polyunsaturated Fat: 5g | Cholesterol: 22mg | Sodium: 208mg | Fiber: 1g | Sugar: 17g
    Course: Dessert
    Cuisine: American
    Author: Tonia Larson

    Cookie Bars

    Brown Butter Chocolate Chip Bars | Brown Butter Snickerdoodle Blondies | S’mores Bars

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    About Tonia Larson

    Hi! I’m Tonia, the owner and recipe creator at The Gunny Sack, where I’ve shared easy recipes for busy people for 14+ years! My family-friendly meals, easy side dishes, and delicious desserts include mouthwatering photos, dynamic videos, and step-by-step instructions to help you cook at home.

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    Comments

      4.75 from 8 votes (7 ratings without comment)

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      Recipe Rating




    1. Denise Moss says

      February 18, 2025 at 5:00 am

      5 stars
      My favorite go to cookie bar recipe!!

      Reply
    2. janet says

      February 28, 2019 at 1:26 pm

      if I wanted to cut the recipe in half, what size pan would I use? These look so good, but our family is small! Could I freeze these? Thank you!

      Reply
    3. Cassie says

      September 25, 2017 at 12:40 pm

      Could I leave out the peanut butter? We have peanut allergies!! THanks!!!!

      Reply
    4. Laura says

      July 27, 2017 at 9:46 am

      I don’t have a stand mixer can i just mix with regular hand,mixer

      Reply
    5. Lyn Olson says

      February 25, 2016 at 1:02 pm

      These are delicious! However, a 15×10 pan is TOO small!!! I had dough falling over the sides onto the bottom of my oven and burning on the heating coil!! Next time, I will use the larger size. Might want to take that size pan off the recipe.

      Reply
      • Tonia says

        February 26, 2016 at 8:30 am

        Oh dear! Sorry about the messy oven! I will make a note in the recipe for others. Thanks Lyn!

        Reply
      • Llamb says

        January 26, 2023 at 9:13 pm

        I just made them and wish I had read the comments first, yep baking over and have a mess in the bottom of my stove.

        Reply
        • Tonia says

          January 27, 2023 at 9:06 am

          I’m very sorry to hear that! I’ve never had an issue with it baking over. What are the measurements of your baking pan? I wonder if the pan sizes vary a lot depending on what brand you have.

          Reply
    6. happy,happy,happy sitter says

      February 25, 2016 at 12:52 pm

      can I use all quick oats and elimanate the flour ? I dont really want too use flour if possable and if so would it be 5 cups of quick oats? Thanks for what looks like a nice recipe.

      Reply
      • Tonia says

        February 26, 2016 at 8:35 am

        Hello! I’ve never heard of a baked oatmeal cookie recipe with only oatmeal in it. Maybe if you finely ground the oats into flour, it would work but I would suggest doing a little research before trying it. Best of luck! ~Tonia

        Reply
    7. Beth Holt says

      March 24, 2015 at 8:11 am

      I love your recipes! Any cookie in bar form is a beautiful thing!

      Reply
    8. Rhonda says

      March 24, 2015 at 6:47 am

      Delicious! Making cookies into bars is a perfect thing to make for last minute company!

      Reply
    9. ty says

      March 24, 2015 at 12:00 am

      Can you substitute shortening for anything?

      Reply
      • Tonia says

        March 24, 2015 at 12:03 am

        You can use butter instead of shortening. Best of luck! ~Tonia

        Reply
    10. Dorothy @ Crazy for Crust says

      March 23, 2015 at 9:39 pm

      The texture in these looks absolutely perfect. Pinned!

      Reply
    Tonia Larson from The Gunny Sack.

    Hi, I'm Tonia! Welcome to The Gunny Sack, where I’ve shared easy recipes for busy people for 15+ years! Meet Tonia Larson →

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