If you're a fan of Gluten Free Monster Cookies but also crave the convenience and simplicity of Gluten Free Monster Cookie Bars, you're in for a real treat. Packed with gluten free oats, an abundance of creamy peanut butter, and lots of chocolate and M&M’s, it is scary how good they are! I love using seasonal M&M's (like the Easter, Christmas or 4th of July special editions) when I make this crowd-pleaser for a potluck.
Jump to:
- Recipe Ingredient Notes
- How to make Gluten Free Monster Cookie Bars
- Storage & Freezing
- Dietary Adjustments Recommendations
- FAQ - Gluten Free Monster Cookie Bars
- Join my Gluten Free Community!
- Note about Salt in my Recipes
- Baking in grams
- Note about Ovens and Oven Temperatures
- Substitutions and Modifications
- More delicious Gluten Free Bar Cookies to try
- 📖 Recipe
- 💬 Comments
Recipe Ingredient Notes
Gluten Free Flour: I tested this recipe for gluten free oatmeal peanut butter cookies with my own gluten free flour blend and King Arthur Measure for Measure. Clearly, this recipe will work with other gluten free flour blends. Just make sure the blend does contain some sort of binder like xanthan gum.
Gluten Free Oats: Old-fashioned oats work the best in this recipe for Gluten Free Monster Cookie Bars. If you don't have them on hand, gluten-free quick-cooking oats will work just as fine. Alternatively, you can even use a combination of both types of oats. Just be sure to avoid using instant oats or steel-cut oats.
Peanut Butter: The star ingredient is undoubtedly peanut butter. Personally, I prefer using "conventional" peanut butter brands like Jif or Skippy for baking. These types of peanut butter contain fully hydrogenated vegetable oils, which help maintain stability and prevent separation. In my experience, this makes them more reliable for baking purposes compared to natural peanut butter, which is ideal for snacking. Whether you prefer creamy or crunchy peanut butter, both variations will work well in this recipe. If you have a peanut allergy, you can substitute sunflower seed butter instead. While I haven't tested the recipe with other nut butters like almond butter, it could be worth experimenting with.
M&M's: I use a mixture of Mini M&M's and regular M&Ms. Mars, the maker of M&M, does not label its products gluten-free. Several resources online consider M&Ms gluten-free, therefor I feel very confident recommending them. Please be aware some M&M flavors do contain gluten. Like Pretzel M&M's, which lists wheat flour as an ingredient, and Crispy M&M's which is made with barley malt.
How to make Gluten Free Monster Cookie Bars
The recipe for Monster Cookie Bars is very straight forwards. Make sure the butter and the eggs are at room temperature.
Step 1: To begin, preheat your oven to 350F and position the wire rack in the middle. Take an 8x8 or 9x9 baking pan, spray it with some cooking spray, and line it with parchment paper. Ensure that there is some excess paper hanging over the sides. This will allow you to easily remove the monster cookie bars from the pan once they are baked and completely cooled.
Step 2: In a medium bowl sift or whisk together the gluten-free flour, baking soda, cinnamon, and kosher salt and set aside.
Step 3: In the bowl of a stand mixer or a large mixing bowl, combine the butter (at room temperature), granulated sugar, light brown sugar, and vanilla extract. Use the paddle attachment to mix until light and combined. Around 3-4 minutes. Scrape down the sides of your bowl to make sure everything is combined properly.
Step 4: Add the peanut butter and mix to combine.
Step 5: Reduce the speed of the mixer and add the room-temperature large egg. Mix until combined.
Step 6: Add the flour mixture to the wet ingredients and mix on low speed until a cookie dough forms. Remember to scrape down the sides and paddle of the bowl to ensure thorough mixing.
Step 7: Lastly add the gluten-free oats, M&Ms, and chocolate chips and give the dough a quick stir.
Step 8: Transfer the gluten free cookie bar dough to the prepared pan. With a spatula or your clean hands press the dough in an even layer in the baking dish. Sprinkle the dough with additional M&M candies and chocolate chips, pressing them just slightly into the dough.
Step 9: Bake the gluten free monster cookie bars until the edges are a light golden brown and the center is evenly puffy, around 30-33 minutes. The middle may appear underdone, but it will set as it cools. Slightly underbaking will give these bars their chewy texture. If you use a different size of pan, please adjust the baking time accordingly.
Step 10: Remove the pan from the oven and allow them to cool in the pan for at least 30-45 minutes before cutting them. Sprinkle them with flaky sea salt if you like.
Storage & Freezing
To store them, make sure the gluten free monster cookie bars are cooled completely before transferring them to an airtight container. Keep them at room temperature for up to 3 days or freeze them for the future when a craving for something sweet hits.
To freeze cookie bars, place them in an airtight container for up to 3 months. I like to arrange the fully cooled bars on a sheet tray and place them in the freezer. Once the bars are fully frozen, I transfer them to an airtight container for long-term storage. When it's time to enjoy these delightful treats, simply thaw them at room temperature or gently defrost them in the microwave. Even though I have to admit they are delicious straight from the freezer....
Dietary Adjustments Recommendations
Flour: If you would like to create those Gluten Free Monster Cookie Bars with “regular” All-Purpose flour, please use 125 grams of AP flour instead of the gluten free flour. All other ingredients in the recipe will stay the same.
Oats: If you are not celiac or have a wheat allergy, use your favorite rolled oats in this recipe.
Peanut Butter: Can be replaced with Sunflower butter or other nut butters like Almond Butter. Just try to avoid any brands that are 100% natural since they will lead to a dry cookie bar.
Butter: I like to use Miyoko’s and ForA Vegan Butter. I do NOT recommend margarine or coconut oil.
M&Ms: If M&Ms aren't your thing, replace them with other chocolate candies like Reese's Pieces, Mini Reese's, chopped-up Snickers, nuts, dried cherries or cranberries...
FAQ - Gluten Free Monster Cookie Bars
Replace the butter used with your favorite non-dairy butter and use 3 tablespoons of aquafaba or a flax-egg to replace the egg used in this recipe. To make a flax egg combine 1 Tbsp flaxseed meal (ground raw flaxseed) and 2 .5 Tbsp water and allow to sit for 5 minutes before using in this recipe.
Although oats do not naturally contain gluten, gluten-containing grains can cross-contaminate them during processing. Consequently, individuals with celiac disease or gluten intolerance should actively select oats labeled as "gluten-free". These oats undergo cultivation, harvesting, and processing methods that actively reduce the risk of gluten contamination.
Cookie bars provide a convenient and hassle-free baking experience. Pressing the dough into a single pan allows for quicker preparation compared to portioning individual cookies. Additionally, cookie bars have a delightful, soft, and chewy texture thanks to their extended baking time. They are also effortless to transport and serve at events or gatherings.
Join my Gluten Free Community!
Note about Salt in my Recipes
I use Diamond Kosher Crystal Salt in all of my recipes unless otherwise stated. If use use a different brand or kind of salt in your kitchen please adjust accordingly since some salts can be saltier. If you use Morton’s Kosher Salt please be aware that their salt granules are smaller in size, denser, and crunchier and twice as salty.
Baking in grams
I share my recipes in grams and by weight since baking by weight is the most accurate way to bake. Digital Scales are very affordable and easy to use. You can purchase them on Amazon for less than a set of measuring cups. For small amounts under 10 grams, I like to use this Precision Pocket Scale. Measuring cups are very inaccurate which can cause significant errors when it comes to gluten-free baking or baking in general. Especially since I bake with gluten-free flours which weigh differently than “regular” flours. I do provide some ingredients like spices and leavening agents in measuring spoons. To learn more about Baking with a digital scale, make sure to check out my post about Baking by weight.
Note about Ovens and Oven Temperatures
All my recipes are tested and developed with a conventional oven. I always bake my baked goods on the rack placed in the MIDDLE of my oven. This way the heat coming from the bottom will not burn my baked goods.
If you are baking with convection (fan-forced), please adjust the recipes accordingly. Convection oven can cause baked goods to dry out quickly and still be raw inside. Since takes at least 15-20 minutes for a standard American Oven to be fully preheated. I highly recommend investing in an Oven Thermometer.
Substitutions and Modifications
Any dietary or ingredient modifications/substitutions to this recipe may alter the end result in appearance and taste. I test my recipes several times as published in this post and The Gluten Free Austrian Blog is not responsible for the outcome of any recipe you find on our website.
More delicious Gluten Free Bar Cookies to try
📖 Recipe
Gluten Free Monster Cookie Bars
Indulge in the chewy goodness of Gluten Free Monster Cookie Bars packed with oats, peanut butter, chocolate, and M&M's. These delectable treats are perfect for satisfying your sweet tooth and are incredibly easy to make.
Ingredients
Gluten Free Monster Cookie Bars
- 113 grams unsalted butter, room temperature
- 100 grams light brown sugar
- 40 grams granulated white sugar
- 120 grams peanut putter
- 1 large egg, room temperature
- 1 teaspoon vanilla extract
- 130 grams gluten free multi purpose flour
- ½ teaspoon baking soda
- ½ teaspoon kosher salt
- ½ teaspoon ground cinnamon
- 100 grams gluten free old fashioned oats
- 100 grams M&Ms
- 115 grams chocolate chips
For decorating
- Additional M&M's
- Additional Chocolate Chips
For Finishing
- Flaky Sea Salt (Optional)
Instructions
How to make Gluten Free Monster Cookie Bars
- Begin by preheating your oven to 350F and positioning the wire rack in the middle. Take an 8x8 or 9x9 baking pan, grease it with cooking spray, and line it with parchment paper. Make sure to leave some excess paper hanging over the sides for easy removal of the monster cookie bars later.
- In a medium bowl, sift or whisk together the gluten-free flour, baking soda, cinnamon, and kosher salt. Set aside.
- With a stand mixer fitted with the paddle attachment or a hand mixer, cream together room-temperature butter, granulated sugar, brown sugar, and vanilla extract.
- Mix in peanut butter until well combined.
- Add a room-temperature egg and mix until fully incorporated.
- Gradually add the flour mixture to the wet ingredients and mix until a cookie dough forms.
- Stir in gluten-free oats, M&Ms, and chocolate chips.
- Transfer the gluten-free cookie bar dough to the prepared pan. Use a spatula or your hands to press the dough evenly into the baking dish. Sprinkle additional M&M candies and chocolate chips on top, gently pressing them into the dough.
- Bake the gluten-free monster cookie bars for approximately 30-33 minutes, until the edges turn a light golden brown and the center becomes puffy. The center might appear slightly underdone, but it will set as it cools. This slight underbaking contributes to the chewy texture of the bars. Adjust the baking time accordingly if using a different pan size.
- Remove the pan from the oven and allow the bars to cool in the pan for at least 30-45 minutes before cutting them. Optional: Sprinkle flaky sea salt on top for added flavor.
Notes
Storage: To store them, make sure the gluten free monster cookie bars are cooled completely before transferring them to an airtight container. Keep them at room temperature for up to 3 days or freeze them for the future when a craving for something sweet hits.
Peanut Butter: Can be replaced with Sunflower butter or other nut butters like Almond Butter. Just try to avoid any brands that are 100% natural since they will lead to a dry cookie bar.
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Jessica says
Is there any concern with doubling the recipe and using a 9x13 pan?
Daniela says
no, this should totally work in a 9x13.
Melissa DeVit says
Do you think I could make this recipe without the oats. I can’t tolerate them.
Daniela says
no, I recommend using my Gluten Free Cookie Bar Recipe instead
Olivia says
Can you do a conversion for metric measurements? Google is giving me all kinds of different answers that don’t make sense. Thanks!
Daniela says
It’s mentioned several times on my website that I only share my recipes in grams/weight. I recommend investing in a digital kitchen scale.
Michelle says
These are delicious! I made these for a GF friend as well as regular monster bars so we could do a taste test and everyone liked these SO much better. 5 stars!