These Monster Cookie Bars are loaded with oats, peanut butter, and chocolate. All the flavors of the classic cookie but in an easy cookie bar form. A perfect dessert bar for lunch boxes, parties, and potlucks!

Monster cookie bars staggered and piled on parchment paper.

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Why We Love These Monster Cookie Bars

A simple cookie bar recipe that only requires basic pantry staples.
These dessert bars are a huge crowd pleaser.
A family favorite! Who doesn't love the combination of peanut butter and chocolate?!
The best sweet treat for bake sales, parties, potlucks and packed in lunch boxes.
These cookie bars have an incredible chewy texture with lots of chocolate and peanut butter flavor that is undeniably delicious!

Monster Cookie Bars Recipe Ingredients

Brown Sugar
White Sugar
Large Eggs
Pure Vanilla Extract
Honey
Baking Soda
Salt
Salted Butter
Creamy Peanut Butter
Old Fashioned Rolled Oats
Whole Wheat Flour
Semi-Sweet Chocolate Chips
Butterscotch Chips
Candy Coated Peanut Butter Pieces

Substitution Suggestions

Pure Vanilla Extract: I strongly recommend using pure extracts. Imitation extracts can leave an unwanted after taste in your baked goods.
Honey: This is the secret ingredient for making these cookie bars extra chewy and soft. If you need to substitute you can use light corn syrup or molasses, or omit it, however the bars will be a bit more crunchy.
Salted Butter: Feel free to use unsalted butter but I suggest adding an extra ¼ teaspoon of salt to the cookie dough.
Creamy Peanut Butter: I like creamy peanut butter best because it creates the best texture in the cookie bars. Crunchy peanut butter can be used but the bars won't be as chewy. If using crunchy I would decrease the oats by ¼ cup. You can use a creamy almond butter if needed too.
Rolled Oats: Quick oats can be used, the cookie bars will be more puffy and less chewy. Rolled oats create the best texture.
Whole Wheat Flour: All purpose flour or white whole wheat flour can be used. I like the extra flavor of the whole wheat flour.
Chocolate Chips & Butterscotch Chips: You can substitute any flavor of chips you like. Dark chocolate chips, milk chocolate or peanut butter chips are all great options. You can also substitute with nuts, dried fruits, or pretzels pieces. Just make sure you are using the same amount.
Candy Coated Peanut Butter Pieces: I always opt for the dye free versions due to allergies so I like to use the Little Secrets Peanut Butter Pieces. You can use Reese's Pieces. To substitute you can use candy coated chocolate drops, M&M's or other candies.

This monster cookie bar recipe is a huge hit with the family and friends. If you love the classic monster cookies then you'll love these bars too.

How to Make Monster Cookie Bars

First, line a 9x13 baking dish with parchment paper or grease with non stick cooking spray.
In the bowl of a stand mixer fitted with the paddle attachment or in a large bowl with electric mixer, beat together the brown sugar, granulated sugar, eggs, vanilla extract, honey, baking soda and salt until smooth.
With the mixer on low speed, drizzle in the melted butter.

Wet ingredients completely creamed together in large metal mixing bowl.

Peanut butter, oats, and flour mixed into wet ingredients.

Next, add the peanut butter, rolled oats, and whole wheat flour and mix until fully combined.
Stir in the chocolate chips, butterscotch chips and peanut butter pieces.
Now place cookie dough in prepared baking pan and gently press into an even layer.

Chocolate chips, butterscotch chips and candy folded into dough with pink spatula.

Cookie dough gently pressed in parchment lined 9x13 baking dish.

Preheat the oven to 350°F. Let the cookie dough rest on the counter while the oven preheats.
Bake bars in preheated oven on center rack for 20-25 minutes until the edges are golden brown and the center is no longer glossy.
Let bars cool completely, then slice into 24 bars and serve.

Monster cookie bars sliced into 24 bars.

Cookie bars are such an easy dessert to make for family, parties and potlucks. Here are some other super delicious cookie bar recipes to try:

Storing Monster Cookie Bars

Storing: Store the cooled cookie bars in an air tight container. Keep them in a cool dry place and they'll stay fresh for 4-5 days. If you notice the leftover bars starting to get a little dry, add a piece of bread or a flour tortilla to the container. It will add moisture back into them.

Freezing: These monster cookie bars freeze great! Place the baked and cooled bars in a freezer safe airtight container in single layers, between pieces of wax paper. Or you can individual wrap them in plastic wrap and then place in a freezer safe container or zip top bag. Label, date and freeze. The bars will last 3-4 months in the freezer.

Thawing: When you are ready to enjoy a delicious bar, simply let them thaw at room temperature for at least 30 minutes.

Side view of three monster cookie bars stacked in front of more bars.

Heather's Favorite Tools for this Recipe

I don't think I could live without my KitchenAid Stand Mixer. It's the best tool ever for making these cookie bars and so many other different things.
These nestled mixing bowls are my favorite for prepping ingredients.
Long ago, I used to be a Pampered Chef consultant and I still prefer their baking tools and pans to any others. They're baking pans are the ones I primarily use. Find yourself a consultant, host a party and treat yourself to a set.
I really like these Pyrex baking dishes too!
Pre-cut parchment paper is a life saver and so easy. No cutting my fingers!
This ice cream scoop is the best. It makes dishing out hard ice cream easily.

Tips for the Best Monster Cookie Bars

Gather all your ingredients before you start baking. It is so much easier to bake when all your ingredients are ready. Plus, there is less room for error. Like forgetting an essential ingredient. I'm not saying I've done this, however, I am speaking from experience!
Always read the recipe from start to finish before you start. Again, I am speaking from experience.
Line the baking dish with parchment paper leaving an inch overhang on the long edge so you can easily lift the bars out of the pan once cooled.
Always fluff your flour and then spoon and level it to measure. Doing this will prevent too much flour from being added and ultimately making the bars dry.
To get the best chewy monster cookie bars, use the honey. If there is an allergy concern, substitute it with molasses or light corn syrup. This is a secret ingredient that helps keep the cookies extra chewy.
For best results let the dough rest while the oven preheats. It doesn't need to be chilled, just rested. Resting the dough allows the oats to absorb all the moisture from the melted butter, eggs, brown sugar and honey creating delightful chewy cookie bars.
Let bars cool completely before slicing. They'll hold their shape once cooled.
To get clean cuts, line the baking pan with parchment paper then once the bars are cooled lift them out of the pan. Using a sharp knife, slice in one smooth cut. Do not use a sawing motion to cut bars.
Take these chewy bars over the top and serve them with a scoop of ice cream for a yummy dessert sundae!

Monster cookie bars layered on top of each other in two columns.

More Dessert Bar Recipes:

Cheesecake Swirl Brownies
Apple Blondies
Lemon Bars
No Bake Cookies N Cream Cheesecake Bars
Oatmeal Fudge Bars
Pumpkin Bars with Cream Cheese Frosting
No Bake Scotcharoos
Coconut Brownies
Rocky Road Brownies
Rhubarb Custard Bars

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Monster Cookie Bars

Course: Dessert

Cuisine: American

Prep Time: 25

Cook Time: 20

Servings: bars

Author: Heather

Ingredients

½ cup brown sugar, lightly packed
½ cup white sugar
2 large eggs
1 teaspoon pure vanilla extract
1 teaspoon honey
1 teaspoon baking soda
½ teaspoon salt
½ cup salted butter, melted
1 cup creamy peanut butter
2½ cups old fashioned rolled oats
½ cup whole wheat flour
¾ cup semi-sweet chocolate chips
¾ cup butterscotch chips
¾ cup candy coated peanut butter pieces

Instructions

Line a 9x13 baking dish with parchment paper or grease with non stick cooking spray.
In the bowl of a stand mixer fitted with the paddle attachment or in a large mixing bowl with hand beaters, beat together the brown sugar, granulated sugar, eggs, vanilla extract, honey, baking soda and salt until smooth.
With the mixer on low speed, drizzle in the melted butter.
Add the peanut butter, rolled oats, and whole wheat flour and mix until fully combined.
Stir in the chocolate chips, butterscotch chips and peanut butter pieces.
Place cookie dough in prepared baking dish and gently press into an even layer.
Preheat the oven to 350°F. Let the cookie dough rest on the counter while the oven preheats.
Bake bars in preheated oven on center rack for 20-25 minutes until the edges are golden brown and the center is no longer glossy.
Let bars cool completely, then slice and serve.

Nutrition

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