Monster cookie bars are ooey gooey peanut butter, oatmeal, and M&M filled dessert bars that are bound to put a smile on your face!
This monster cookie bar recipe (inspired of course by our delicious monster cookies) are a favorite around here. Grab a cold glass of milk and enjoy!
Monster Cookie Bars
Monster Cookie Bars
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Monster Cookie Bar Ingredients
- Butter – Softened. We like salted butter, but unsalted is fine too.
- Brown sugar – We use light brown sugar, but dark will also work. When measuring, pack lightly.
- White sugar – Granulated.
- Egg – Large.
- Vanilla – Real vanilla extract, not imitation.
- Peanut butter – Creamy is our preference, but crunchy can be substituted.
- Flour – All purpose, make sure it’s not self rising!
- Baking soda – Not baking powder!
- Oats – Quick cooking (not instant oats or rolled oats).
- Chocolate chips – I love semi-sweet, but feel free to use what you like/have on hand.
- M&Ms – I like to use extra on top for a pop of color.
Butter, peanut butter, sugar, flour, egg, vanilla, baking soda, chocolate, M&M’s, oats.
How do you make monster cookie bars? (step-by-step)
⭐ First, cream together butter and both sugars. Add in the egg and vanilla, mixing well. Stir in peanut butter, then add in flour and baking soda.
⭐ Next, add in the quick oats. Once well mixed, stir in the chocolate chips and M&Ms. Spread mixture into the bottom of a lined baking pan. Top with extra M&M’s.
⭐ Then, bake until edges are just beginning to brown.
⭐ Finally, allow to cool completely before cutting into squares.
Cream butter and sugars, then add each additional ingredient to create dough.
Preparation
Can you make monster cookie bars ahead of time?
Yes! Bake and store them in an air tight container for several days at room temperature, or up to a week in the refrigerator. Eat as-is or warm in the microwave or in the toaster oven.
Can I use natural peanut butter?
We strongly suggest using normal peanut butter and not natural or low fat peanut butter for this recipe. The recipe should still work with natural peanut butter, but we have not tested extensively.
How do I know when the monster cookie bar recipe is done baking?
The cookie bars will be done baking when they start turning golden brown along the edges. Do not wait until the cookie is browned all over, or it will be over baked.
Can you freeze monster cookie bar dough?
For sure! Wrap it tightly in plastic wrap, then place in a freezer bag or wrap again in foil. Freeze for up to six months, then thaw in the refrigerator before pressing into a pan and baking.
Alternatively, press into a parchment lined pan and freeze. Remove frozen dough from pan and wrap as described above. Place pre-shaped dough in pan when ready to bake.
Press dough into pan, add extra M&M’s to top, then bake until edges are slightly browned.
Leftovers and storage
How long do monster cookie bars last?
Leftovers will keep 3 – 4 days when kept at room temperature, or up to a week in the refrigerator. For best results store in an airtight container.
Do you have to refrigerate monster cookie bars?
It is not necessary to refrigerate the cookie bars, but they will keep longer in the refrigerator.
Can you freeze monster cookie bars?
Yes, they can be frozen before or after baking. See our preparation section above for details on freezing the dough.
To freeze baked cookie bars, allow them to cool first, then slice store in a freezer safe air-tight container.
Can you bake the dough from frozen?
Yes! If you’ve frozen the dough spread into a pan or frozen pan-shaped dough, go ahead and cook from frozen. You’ll add about an extra ten minutes to the cook time, just pay attention to when they start to brown on the edges.
Allow to cook before slicing.
Tips, tricks, and Frequently Asked Questions
🌈 Use specific M&M colors to celebrate different holidays and occasions! Pink for new baby girl, orange and blue for your favorite sports team (Go Gators!), or red and green for Christmas!
🍫 Try different kinds of chips in your bars – these are semi sweet chocolate chips, but try milk chocolate, peanut butter chips, butterscotch chips, or even white chocolate.
🎁 The perfect housewarming gift! Bring the dough frozen in the bottom of a new pan with directions on how to bake. Two gifts in one!
🧈 If you don’t have parchment paper, use a cooking spray (our our cooking spray substitute) so your bars don’t stick.
Then stack them like this and send a picture to all your friends so they are jealous that you have cookies.
What to eat with homemade monster cookies (serving suggestions)
These are a fun after-dinner treat following a yummy meal of fettuccine alfredo, butter chicken, or baked honey mustard salmon! And get your greens in with some roasted asparagus or sautéed vegetables.
Then send this picture to your mom or sister.
Other cookie recipes to try
- Best sugar cookie recipe
- Homemade peanut butter blossoms
- Cookies and cream cookies with Oreos
- White chocolate cranberry oatmeal cookies
- See all our best cookie recipes!
More dessert bars you’ll enjoy
- Sugar cookie bars
- Magic cookie bars
- Best lemon bar recipe
- Salted chocolate caramel bars
- Chocolate chip toffee oatmeal bars
- See all our dessert bar recipes
But also, maybe ask if anyone wants to come over and share.
Other incredible desserts
- Watergate salad recipe
- Homemade cheese Danish
- Italian cream soda recipe
- Cake balls recipe
- See all our dessert recipe ideas!
Confession, I don’t always wait until they’re completely cooled.
Tools we love
- Baking dish – I love this dish, it can go from freezer to oven and even has a lid!
- Stainless steel spatula – Lift out the absolute perfect square with this spatula.
😍😍😍
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How to Make Monster Cookie Bars
Monster Cookie Bars
Ingredients
- ½ cup butter softened
- ½ cup brown sugar packed
- ½ cup granulated sugar
- 1 egg
- 1 teaspoon vanilla
- ½ cup creamy peanut butter
- ½ cup all purpose flour
- ½ teaspoon baking soda
- 1 ½ cups quick oats
- 1 cup semisweet chocolate chips
- 1 cup M&Ms plus more for topping
Instructions
- Using a hand mixer or stand mixer on medium speed, cream together butter and both sugars.
- Add in the egg and vanilla, mixing well.
- Mix in peanut butter, then add in flour and baking soda, scraping down the sides of the bowl as necessary.
- Add in the quick oats. Once well mixed, stir in the chocolate chips and M&Ms.
- Spread mixture into the bottom of a parchment lined 9x13 baking dish. Sprinkle the top with M&Ms, pushing them in slightly.
- Bake at 350 degrees for 20 to 25 minutes, until edges are just beginning to brown.
- Allow to cool completely before cutting into squares.
Notes
Nutrition
Love monster recipes? Try this monster bundt cake for Halloween!
Monster Cookie Bars
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Mary says
Fantastic! I agree no nuts they would take away from all the chocolatey goodness. My dentist will be so pleased. Lol
Wendy Genaros says
I would leave the nuts because we have some who do not like nuts in the family.
Vicki in Birmingham says
No nuts for me…but only because I developed a tree nut allergy about 4 years ago. All who can have them ENJOY!!!
Darcie says
I like mine chewy with no nuts.
Carol says
I prefer thick and chewy
Judy says
I haven’t tried these yet but intend to since I already love the cookies. I like my bars thick and chewy the same way I love my cookies. No nuts in mine either. Judy
Diana M. Cox says
I saw these on facebook and they looked so good I had to try it out! They came out chewy and delicious. I may try to add coconut next time, but it’s not really needed.
Debbie Dean says
Thick and chewy all the way!!!!
SONJA MOURE says
soft and chewy with candies
Roger Mccroskey says
No nuts , changes the texture. Thick for sure, they turned out great, just don’t over bake
Denise says
Thick & Chewy