Monster Cookie Recipe

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My Monster Cookie recipe creates scrumptious chewy cookies, and they’re jam-packed full of chocolate and peanut butter flavor! The best part? You’ll find M&Ms in every bite! Oatmeal monster cookies are dessert perfection!!

monster cookie recipe.


Making a batch of cookies from scratch is SO worth the time — there’s nothing as special as a homemade dessert.

Honestly, once you realize that it’s simple, and the flavor is SO much better than store bought treats, you’ll never go back!

M&M chocolate chip cookies ingredients.

So, what are monster cookies? In a nutshell, it’s an oatmeal cookie, packed with all of the popular cookie ingredients: peanut butter, candies, and chocolate — oh my!

Everyone’s recipe is a little different, but these monster cookies are the gooiest, chewiest, and tastiest out there!

Many of the ingredients we use to make these M&M chocolate chip cookies are also in my delicious trail mix cookies recipe. Give that recipe a try next time! 

Or, just keep things classic with the best chewy chocolate chip cookies ever!! Or this incredible Christmas cookie bars recipe.

making monster cookie dough.

Ingredient Notes and Substitutions

  • Unsalted Butter – If you use regular salted butter, leave out the additional salt in the recipe. Either way, it should be softened but still cold.
  • White Sugar and Light Brown Sugar – You may be asking, “Why use both?” Because just the right amount of brown sugar makes these cookies super chewy!

    If that’s not your jam, then use all white sugar.
  • Peanut Butter – Creamy or chunky PB – it’s your choice. I prefer creamy, but this monster cookie recipe is for you!
  • Old Fashioned Rolled Oats – Don’t use instant oats or steel-cut rolled oats! Traditional rolled oats are flat, so they absorb the liquid ingredients better.
  • M&Ms – Either mini or regular size is fine. Save some to press into the tops of the cookies just before baking.
monster cookie dough in bowl.

This recipe makes really large cookies! If you prefer smaller, regular-sized oatmeal monster cookies, just use a smaller cookie scoop!

But you will need to make an important change to the monster cookie recipe shown below. 

Shorten the bake time. Rather than bake each batch for 20 minutes at 300°F, you’ll bake for 12-15 minutes at 350°F.

Because they’re smaller, you can increase the heat and decrease the bake time!

Storing and Freezing Oatmeal Monster Cookies

Baked cookies can be kept at room temp. As long as they’re in an airtight container, they’ll stay fresh for 5 days or so.


If your cookies become a bit hard and stale, microwave them for 30 seconds. Put them on a plate covered with a damp paper towel and they’ll come out warm and soft!!

The baked cookies freeze beautifully, and so does the unbaked cookie dough!! 

Freezing Monster Cookie Dough

I recommend scooping out the dough before you freeze it. Otherwise, you’ll have a solid block of cookie dough, and that will take a LONG time to thaw.

I like to wrap them separately in plastic wrap or parchment  – it prevents them from freezing together.

Toss the unbaked cookie dough balls in an airtight container or zip top bag, and it should stay good for up to 2 months. Let it thaw in the fridge before baking.

In the fridge, the unbaked dough will keep for up to 4 days. 

scoops of monster cookie recipe on baking sheet.
Why are they called monster cookies?

The “monster” name is a reference to Frankenstein’s monster, because it’s made up from so many different parts! 

Why do my monster cookies go flat?

One possible reason for flat cookies is using ingredients that are too soft, especially the butter. It should be softened, but still cool to the touch.

If the climate is warm, you can chill the dough for 30 minutes in the fridge or 15 minutes in the freezer before baking – the cookies will spread less and maintain most of their height.

Your oven could also be too hot, melting the butter before the dough has a chance to form. So be sure to follow the timing and temperature steps outlined in this monster cookie recipe!

monster cookies stacked.

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monster cookie recipe.

monster cookies closeup.

Monster Cookie Recipe

Donna Elick
My Monster Cookie recipe is an easy to make treat! With peanut butter, M&Ms, and chocolate chips, they're the BEST oatmeal monster cookies!
5 stars from 3 reviews
Tried this recipe?Please comment and review!
Prep Time 10 minutes
Cook Time 20 minutes
Total Time 30 minutes
Course Dessert
Cuisine American
Method Oven
Servings 12 cookies


  • 1/2 cup unsalted butter, softened but still cold
  • 1/2 cup granulated sugar
  • 1/2 cup packed light brown sugar
  • 1/2 cup creamy peanut butter
  • 1 large egg
  • 1/2 teaspoon vanilla extract
  • 1 1/4 cups all-purpose flour
  • 1/2 teaspoon baking soda
  • 1/2 teaspoon salt
  • 1 cup old fashioned rolled oats, not instant
  • 1 cup M&Ms, plus extra to top cookies
  • 1/2 cup mini semi sweet chocolate chips


  • Preheat the oven to 300°F. and line a cookie sheet with parchment paper. *See Notes
  • Using an electric hand mixer or stand mixer fitted with a beater attachment, cream together butter, white sugar and brown sugar in a mixing bowl.
  • Add the peanut butter, egg, and vanilla, and mix well on high speed to combine.
  • Reduce speed to low and add in flour, baking soda, and salt. Mix just to combine but don’t overmix or your cookies will be tough and dry.
  • Using a wooden spoon or silicone mixing spatula, fold in rolled oats, 1 cup M&Ms, and mini chocolate chips.
  • Using a 3-tablespoon cookie scoop, portion out the dough and arrange the balls about 2 inches apart on the prepared cookie sheet.
  • Bake for 20-22 minutes, or until the edges start to brown and the center is soft.
  • Remove cookies from the oven and while still warm, sprinkle with extra M&Ms (optional).
  • Let the cookies cool on the cookie sheet for 20-30 minutes. This allows the center and chocolate to set. If you prefer, serve while warm and gooey.

Donna’s Notes

A 3-tablespoon cookie scoop makes cookies that are a little bit larger than traditional cookies. For this reason, they need to bake at a lower temperature for a longer period of time. Otherwise, they’ll burn on the outside before the inside is cooked.
If you prefer to use a traditional 2-tablespoon sized cookie scoop, increase oven heat to 350°F. and bake the cookies for 12-15 minutes.


Serving: 1 | Calories: 422cal | Carbohydrates: 51g | Protein: 7g | Fat: 22g | Saturated Fat: 11g | Cholesterol: 39mg | Sodium: 212mg | Sugar: 33g | Fiber: 3g | Calcium: 49mg | Iron: 2mg

All nutritional information is based on third party calculations and is only an estimate. Each recipe’s nutritional value will vary depending on the ingredients used, measuring methods, and portion sizes.

Tried this recipe?Let us know how it was!
monster cookie recipe.

Originally published September 2022

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  1. Been making My signature Monster Cookies for the past 40 yrs and as you said there are many variations of this recipe because there is no flour in mine and my one batch makes 18 dozen. They are called Monster Cookies because they are so good you won’t want to share and that is a sign of a true Cookie Monster.

    1. I absolutely love these cookies. I thought they were called Monster Cookies because of the size of them. I have a recipe and I’m thinking it called for a dozen eggs and much more peanut butter, sugar and brown sugar. Of course everything else is increased as well. Either way, so good.

    1. Hi Theresa,
      You could try substituting sunflower butter for the peanut butter in this recipe. Otherwise, maybe you’d enjoy our trail mix cookies recipe. Just omit the peanuts, or substitute sunflower seeds for the peanuts! I hope this helps.

      TSRI Team member,

  2. 5 stars
    This was such a fun recipe to make with my kids. They loved how big the cookies were, and loved how it tasted even more. Definitely making these again with them.

  3. 5 stars
    oh my goodness! these monster cookies are absolutely delicious! i couldn’t stop eating them! thank you, Donna and Chad, for another amazing recipe from The Slow Roasted Italian.

  4. 5 stars
    i made these monster cookies last night and they were a breeze to whip up! instead of M&Ms, i used raisins because that’s what i had on hand. they turned out delicious!

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