Monster Cookie Bars
This Post May Contain Affiliate Links. Please Read Our Disclosure Policy.
These Monster Cookie Bars are about to become your new obsession! Made with peanut butter, oats, M and M candies, and chocolate chips for an easy bar treat. And they are ready to bake in minutes!
The Best Chewy Monster Cookies Bar Recipe!
Oh, let me spill the cocoa beans about my all-time favorite kid-friendly, Halloween recipe – these scrumptious Monster Bars! These babies are like a wild party in your mouth, with an irresistible chewy texture that’s just oh-so-yum. I love a good Monster cookie and I love them in bar form – because let’s face it…bar cookies are way easier!!
Where else can you throw in peanut butter, chocolate chips, and colorful M&M candies all in one place? It’s like a candy store exploded in my kitchen, and I am all here for it.
The secret sauce here is that creamy peanut butter. The peanut butter mixes so well with the vanilla, creamy butter, and chocolate . It’s a mix-masterpiece, I tell you!
But the best part? The soft and chewy texture that happens when those monster bars come out of the oven, all golden and absolutely delicious. It’s like they’re saying, “Grab me now or regret it later!”
They are wonderfully simple and they are always turn out a crowd-pleaser. And if you love a peanut butter oatmeal cookie then I know you will love this Monster peanut butter oatmeal cookie bar.
So, the next time you’re feeling like unleashing some baking chaos in the sweetest way possible, give these Monster Bars a whirl. You won’t regret it – just remember to save a square for yourself before they disappear in a cookie monster frenzy!
See Also:
- Pucker up and enjoy one of these homemade lemon cookies with easy lemon glaze drizzled over them!
- Coconut macaroons are an easy gluten free chewy coconut cookie. Dip in chocolate for an easy chocolate treat!
- Grab a jar of peanut butter and make these wonderfully easy old fashioned peanut butter cookies with criss cross pattern on top!
- Make these brown sugar chocolate chips cookies made with 100% brown sugar making them wonderfully chewy!
Why You Will Love Monster Cookie Bars
- Irresistible Chewiness. These Monster Bars are the kings and queens of chewy delights. If you’re a fan of that perfect, gooey texture in your treats, these bars have got it down to an art.
- Quick To Mix Up – These are a great last minute dessert to throw together to bring to a party or to serve guests.
- It’s fun to customize. You can customize this recipe to your liking by adding different mix-ins, such as nuts, dried fruit, candy pieces, or pretzels. You can also use different types of chocolate chips or flour.
4 Main Components To These Monster Cookie Bars:
Quick Oats Vs. Old Fashioned Oats
I recommend using old fashioned oats because of their larger heartier texture. And since these monster cookie bars are chewy peanut butter oatmeal cookie bar the type of oats matter. Using old fashioned oats will give you a chewier thicker textured bar.
But you can swap and use quick oats. Quick oats are a bit more broken down and dustier in my opinion to use.
Type Of Peanut Butter
I like to use a smooth creamy peanut butter for these bars. I don’t recommend using a natural peanut butter because it can be a bit oilier in texture. I usually use Jif or Skippy.
You could swap and use a chunky peanut butter for a bit of extra crunch in these cookie bars!
Chocolate Chips
I used regular semi-sweet chocolate chips, but you could use chocolate chunks or mini sweet chocolate chips. You could also use chopped chocolate.
And if you wanted more chocolate flavor then stir in some peanut butter chips or try swapping and using white chocolate chips.
Candies
Traditionally a monster cookie bar uses colorful m&m candies stirred in. But you could easily swap and use Reese’s Pieces or another favorite candy! I also stirred in chopped peanut butter cups as well.
I love to around the holidays use Christmas M&M’s and stir in white chocolate chips for a fun festive Christmas cookie bar.
Ingredients Needed for Monster Cookie Bars
- 1 ½ cups (180 g) all-purpose flour – Be sure to measure your flour correctly by spooning into your cup and leveling it off. Do not pack it down or you will end up with too much flour resulting dry, crumbly cookie bars.
- 2 cups (198 g) old fashioned oats- Old fashioned oats are the best choice for this recipe because they have a chewier texture than quick oats.
- 1 teaspoon baking powder
- 1 teaspoon baking soda
- ½ teaspoon salt
- 1 cups (213 g) light brown sugar – Light brown sugar is best for this recipe but dark brown sugar can also be used
- 1/2 cup (100 g) granulated sugar
- 1 cup (2 sticks, 226 g) unsalted butter, softened to room temperature – I like to unsalted butter rather than salted butter because it contains less water so it creates a chewier cookie and I can control the amount of salt. But if using salted, reduce the added salt.
- 2 large eggs, room temperature – Make sure the eggs are room temperature so they blend easily into your cookie batter. If you use cold eggs it will seize up the butter that has been creamed and aerated.
- 2 teaspoons vanilla extract
- ½ cup (135 g) smooth peanut butter – I used creamy peanut butter for this recipe because it gives the monster cookie bars a creamy texture.
- 1 cup (170 g) semi-sweet chocolate chips
- 1 cup (170 g) M&M candies- M&M candies are a fun and colorful addition to this recipe, but you can also use other types of candy, like Reese’s pieces such as chopped nuts or dried fruit.
How to Make Monster Cookie Bar Dough
Preheat and prepare pan.
Preheat oven to 350oF. Grease or line a 9×13 baking pan with parchment paper, or you can grease with cooking spray, or line with aluminum foil.
Whisk dry ingredients together.
In a large bowl, whisk together the flour, oats, baking powder, baking soda and salt. Set the bowl aside.
Cream butter and sugar.
In a large mixing bowl with an electric mixer, cream together on medium speed the butter and sugar until light and fluffy, about 2 minutes.
I like to make the cookie dough in the bowl of a stand mixer fitted with a paddle attachment, but you can also use a hand mixer.
Add eggs, vanilla, and peanut butter.
Beat in eggs, one at a time, until smooth and combined.
Beat in vanilla and creamy peanut butter until smooth. Scrape down bowl with a wooden spoon as needed.
Add flour mixture and chips.
Stir in the flour mixture just until combined.
Fold in chocolate chips and M&M candies.
Bake.
Spread the cookie dough into prepared pan. I like to top the cookie dough with more M&M candies and chopped peanut butter cups on top so the bars look pretty when they come out of the oven.
Bake for about 25 minutes just until the edges are lightly golden brown and set.
Remove the dessert bars from the oven and allow to cool completely. Once the baked bars have cooled, remove from the pan and cut into squares.
Recipe Tips
- Use room temperature ingredients. This will help the ingredients to combine more easily and create a smoother batter for these monster cookies.
- Don’t overmix the batter. Overmixing can make the monster cookie bars tough.
- Be careful not to overbake the monster cookie bars. The bars are done when the edges are golden brown and the center is soft but set.
- Let the dessert bars cool completely before cutting them. This will help to prevent the bars from crumbling.
- Use a kitchen scale. For best results I always recommend weighing your ingredients.
Recipe Variations
- Different mix-ins– You can add a variety of different mix-ins to your monster cookie bars, such as chopped nuts, dried fruit, candy pieces, or pretzels.
- Different types of chocolate– You can use any type of chocolate that you like in your monster cookie bars. Milk chocolate, dark chocolate chips, and white chocolate are all good options. You can also use a mix of different types of chocolate.
- Different spices– You can add different spices to your monster cookie bars, such as cinnamon, nutmeg, or allspice. Just add a pinch or two of your favorite spices to the dry ingredients.
- Different flavored chips– You can use flavored chocolate chips to add extra flavor to your monster cookie bars. Some popular options include peanut butter chips, butterscotch chips, and mint chocolate chips.
- Make vegan – Use a flax egg, and vegan butter to make these vegan monster cookie bars.
- Make a big batch – You can spread the cookie dough into a large rimmed baking sheet, a 10 by 15 inch jelly roll pan to feed a crowd!
- Make gluten free – Use gluten free flour and certified gluten free oats.
Storage Instructions
These monster cookies can be stored in an airtight container at room temperature for up to 3 days or covered in the fridge for up to 5 days. They can also be stored in the freezer for up to 3 months in an airtight container. Thaw at room temperature before serving.
Yes, you can make the bars ahead of time. Just bake the monster cookie bars according to the recipe, then let them cool completely. Once the monster cookie bars are cool, wrap them tightly in plastic wrap and store them in the refrigerator for up to 3 days or in the freezer for up to 3 months. When you are ready to serve the bars, thaw them overnight in the refrigerator or at room temperature for 30-60 minutes.
More Recipes to Try
Monster Cookie Bars
Ingredients
- 1 ½ cups (180 g) all purpose flour *spooned and leveled
- 2 cups (198 g) old fashioned oats *see note
- 1 teaspoon baking powder
- 1 teaspoon baking soda
- ½ teaspoon salt
- 1 cups (213 g) packed light brown sugar
- 1/2 cup (100 g) granulated white sugar
- 1 cup (2 sticks, 226 g) unsalted butter softened
- 2 large eggs room temperature
- 2 teaspoons vanilla extract
- ½ cup (135 g) smooth peanut butter
- 1 cup (170 g) semi-sweet chocolate chips
- 1 cup (170 g) candies (I used a combination of peanut butter cups and M&Ms)
Instructions
- Preheat and prepare pan. Preheat oven to 350°F. Grease or line a 9×13 baking pan with parchment paper.
- Whisk dry ingredients together. In a mixing bowl, whisk together the flour, oats, baking powder, baking soda and salt. Set the bowl aside. 1 ½ cups (180 g) all purpose flour 2 cups (198 g) old fashioned oats 1 teaspoon baking powder 1 teaspoon baking soda ½ teaspoon salt
- Cream butter and sugar. In a large mixing bowl, cream softened butter and sugars together until light and fluffy. Beat in eggs one at a time, scraping down bowl as needed. Beat in vanilla and peanut butter until combined. 1 cup (2 sticks, 226 g) unsalted butter 1 cups (213 g) packed light brown sugar 1/2 cup (100 g) granulated white sugar 2 large eggs 2 teaspoons vanilla extract ½ cup (135 g) smooth peanut butter
- Add flour mixture and chips. Stir in the flour mixture just until combined. Fold in chocolate chips and candies. 1 cup (170 g) semi-sweet chocolate chips 1 cup (170 g) candies
- Bake. Spread the batter into prepared pan and bake for about 25 minutes just until the edges are golden brown and set. The center of the bars will still be slightly soft. Remove the bars from the oven and allow to cool completely and the center is set. Once the bars have cooled, remove from the pan and cut into squares.
Notes
- Storage: These monster cookies can be stored in an airtight container at room temperature for up to 3 days. They can also be stored in the freezer for up to 3 months.
- Make Ahead: Yes, you can make the bars ahead of time. Just bake the monster cookie bars according to the recipe, then let them cool completely. Once the monster cookie bars are cool, wrap them tightly in plastic wrap and store them in the refrigerator for up to 3 days or in the freezer for up to 3 months. When you are ready to serve the bars, thaw them overnight in the refrigerator or at room temperature for 30-60 minutes.
- Substitution Tip: You could make these into cookies. Using a 1 ½-inch cookie scoop, scoop cookies onto baking sheet and bake for 10-12 minutes until edges are golden brown, and middles are set.
- Oats: I recommend using old fashioned oats because of their larger heartier texture. But you can swap and use quick oats. Quick oats are a bit more broken down and dustier in my opinion to use.
- Peanut Butter: I like to use a smooth creamy peanut butter for these bars. I don’t recommend using a natural peanut butter because it can be a bit oilier in texture. I usually use Jif or Skippy. You could swap and use a chunky peanut butter for a bit of extra crunch in these cookie bars!
- Chocolate Chips: I used regular semi-sweet chocolate chips, but you could use chocolate chunks or mini sweet chocolate chips. You could also use chopped chocolate. And if you wanted more chocolate flavor then stir in some peanut butter chips or try swapping and using white chocolate chips.
- Candies: Traditionally a monster cookie bar uses colorful m&m candies stirred in. But you could easily swap and use Reese’s Pieces or another favorite candy! I also stirred in chopped peanut butter cups as well.I love to around the holidays use Christmas M&M’s and stir in white chocolate chips for a fun festive Christmas cookie bar
Hi thank you! It’s delicious. But I wasn’t too sure about the Fahrenheit. 375F or 350F please?
Hi, sorry for the confusion! It’s 375°, I’ll get that fixed, thank you!
You omitted the sofa and changed amount of white sugar in recipe. You call for soda and 1/2 cup white sugar I’m notes above recipe. I didn’t add soda so hope they turn out.
my apologies David – that ingredient got left off by mistake and I adjusted the sugar amount as well.