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!!
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!
Monster Cookie Recipe
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!!
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.
Making a Smaller Monster Cookie
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.
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.
Monster Cookie Recipe FAQ
The “monster” name is a reference to Frankenstein’s monster, because it’s made up from so many different parts!
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!
With love, from our simple kitchen to yours.
Other Fabulous Cookie Recipes
Monster Cookie Recipe
- 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.
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.
Originally published September 2022
Disclosure: Posts may contain affiliate links. If you purchase a product through an affiliate link your price will remain the same and The Slow Roasted Italian will automatically receive a small commission. Thank you for supporting us, it helps us keep creating new recipes.