These Peanut Butter Monster cookies are loaded with creamy peanut butter, chewy oats, colorful m&ms, and gooey semi-sweet chocolate chips! They bake up super thick, with chewy edges and incredibly soft centers.
Monster Cookies Recipe
If there’s one cookie recipe you should make for Halloween this weekend, it’s these Monster Cookies! There’s nothing overly spooky or scary about these cookies… other than the fact that they’re scary delicious. They’re easy to make and are loaded with peanut butter, old-fashioned oats, and colorful m&ms and chocolate chips. But you can play around with the “mix-in” ingredients and really make these cookies your own!
Want to make your cookies look like they came from a fancy bakery? Here’s a little pro-tip: Sprinkle the cookie dough with old-fashioned oats before baking. Then press extra M&MS and chocolate chips on top of the warm cookies when they come out of the oven!
Viola! Your cookies now look like they came from a 5-star bakery.
What is a Monster Cookie?
There are so many monster cookie recipes on the web, and they vary greatly. Some are basically just regular cookies with m&m’s and chocolate chips. Others have oats, nuts, butterscotch chips, or coconut. And then there are the ones that incorporate PEANUT BUTTER.
My version is a combination of all of the above! These peanut butter cookies are loaded with oats, peanuts, M&Ms, cinnamon, vanilla, and of course, chocolate chips! I also use a combination of brown sugar and granulated sugar, which adds depth of flavor. They’re thick, chewy, and so delicious.
Ingredients for Monster Cookies
- Butter: Be sure your butter is at room temperature before you begin baking! Butter that is too cold won’t properly cream.
- Peanut Butter: Creamy peanut butter is king when it comes to these cookies! JIF, Skippy, and Peter Pan brand are all favorites of mine and work great in this recipe! I don’t recommend using chunky peanut butter, natural peanut butter, and definitely not almond butter or other nut butters.
- Vanilla Extract: Adds its signature flavor while enhancing all of the other flavors in the recipe. Be sure to use real vanilla, and not imitation or artificial vanilla.
- Sugar: A combination of granulated sugar and brown sugar sweeten the cookies and add incredible depth of flavor. Do not reduce the amount of sugar.
- Eggs: You’ll use whole eggs and an egg yolk in this recipe. You can save the egg white for another recipe! Just cover it and place in the fridge for up to 2 days. Be sure to use large eggs and bring them to room temperature before baking.
- Flour: The best way to measure this ingredient is with a digital kitchen scale. Otherwise, you’ll want to lightly spoon it into the measuring cup. Never pack your flour, this leads to dry cookies that don’t spread.
- Oats: The combination of old-fashioned oats and quick oats give this cookie recipe incredible texture. Resist the temptation to add more oats, this will lead to cookies that don’t spread well.
- Baking Soda: This chemical agent helps the cookies spread in the oven. Be sure to check that your baking soda isn’t expired.
- Baking Powder: This is my secret ingredient to thick and puffy cookies! Be sure to use fresh baking powder.
- Cinnamon: This spice adds depth of flavor and warmth to the cookie dough. If you dislike cinnamon, you can simply omit, no need to replace it with another ingredient.
- Salt: Although it may sound odd, you never want to skip adding salt to cookies! This ingredient balances the overall sweetness and helps enhance the flavors in the recipe. Try adding a sprinkle of flaky sea salt on top for an extra delicious treat!
- M&M Candies: You can use plain M&Ms for a classic monster cookie. Or use seasonal ones like red & green to celebrate Christmas or white and pink to celebrate Valentine’s Day!
- Semi-Sweet Chocolate Chips: Feel free to use dark chocolate chips, white chocolate chips, or butterscotch chips instead. You could even use a combination of all of the above!
- Salted Peanuts: These nuts add delicious crunch and enhance the overall peanut butter flavor. If you don’t have any on hand, feel free to simply leave them out. Or use pecans or walnuts.
How to Make Monster Cookies
- Make the Cookie Dough: Use a stand mixer or a large mixing bowl and an electric hand mixer for this step. Once you add the dry ingredients into the wet ingredients, mix gently. Over mixing causes dry cookies.
- Chill the Cookie Dough: Cover the bowl and place it in the fridge for 30 minutes, or up to 2 days. If you chill longer than 2 hours, let the dough sit at room temperature for 15 minutes before scooping. When you’re ready to bake, remove the bowl from the fridge.
- Cookie Prep: Preheat the oven and line two large baking sheets with parchment paper. You should do this about 30 minutes before you plan on baking.
- Scooping the Dough: Scoop two tablespoon of dough onto the prepared cookie sheet. Gently press down on each cookie ball, slightly flattening the ball. Sprinkle the top of each cookie with some extra oats, if desired.
- Bake the Cookies: Bake one tray at a time, for about 10 to 12 minutes. The exact baking time will vary depending on your baking sheet and oven.
- Cool the Cookies: Remove them from the oven and cool on the baking sheet for 10 minutes. Then transfer the cookies to a cooling rack and cool completely.
Why Didn’t My Cookies Spread?
This is a common question I receive for this cookie recipe in particular, so I wanted to help troubleshoot. Here are a few reasons your cookies don’t spread enough:
- Too much flour: This is the number one culprit for dry and puffy cookies that don’t spread in the oven. Measure the flour properly by using a digital kitchen scale. Or, fluff up the flour in the bag and lightly spoon the flour into the measuring cup. Fill it until it overflows, then scrape the top smooth with a knife.
- Too many Oats: Similar to flour, oats absorb liquid ingredients. So if you add more oats than the recipe calls for, your cookies will turn out drier than they should.
- Butter is too Cold: For the butter to properly cream, it needs to be at room temperature. Butter that’s too cold won’t break up or bond properly with the other ingredients. This can cause issues for the cookies down the road.
- Wrong Peanut Butter: When it comes to these cookies, not all peanut butter is created equal. Be sure to use traditional creamy peanut butter, like JIF or Skippy.
- Other Change in The Recipe: Did you forget to add the egg yolk? Or did you use small eggs instead of large? Did you use gluten free flour? Or all quick oats instead of a mix?
These seemingly small changes have a large impact. So for best results, follow the ingredient list and method to a T!
Tools for This Recipe
- Electric Hand Mixer or Stand Mixer: You need one of these options to make the cookie dough.
- Large Mixing Bowl: If you’re using a hand mixer, you’ll need a large sturdy bowl to make the cookie dough.
- Cookie Dough Scoop: A large and sturdy cookie scoop is a cookie baking must-have!
- Parchment Paper: A must-have for lining your cookies sheets. Do not sub wax paper or aluminum foil.
- Large Baking Sheets: Light colored cookies sheets work best for baking cookies. That’s because they help reduce over browning in the oven. A dark cookie sheet will work, but may yield darker cookies.
- M&M Candies: Use classic M&Ms or buy seasonal colors to celebrate your favorite holidays!
- Creamy Peanut Butter: Use traditional creamy peanut butter, and not natural peanut butter, which doesn’t work well in this recipe.
- Chocolate Chips: Use your favorite variety of chocolate chips, or a combination of several different chip flavors.
- Salted Peanuts: These add so much delicious flavor and a great crunch to the cookie.
Soft Batch Peanut Butter Monster Cookies
- 1 cup (227g) unsalted butter room temperature
- 1 cup creamy peanut butter room temperature
- 2 teaspoons pure vanilla extract
- 1 and 1/4 cups (269g) light brown sugar, packed
- 1/3 cup (66g) granulated sugar
- 2 large eggs room temperature
- 1 large egg yolk room temperature
- 1 and 3/4 cups (210 grams) all-purpose flour
- 1 cup old-fashioned oats
- 1/2 cup quick oats
- 1 teaspoon baking soda
- 1 teaspoon baking powder
- 1/2 teaspoon ground cinnamon
- 1/2 teaspoon salt
- 1 and 1/2 cups M&M candies
- 1 and 1/2 cups semi-sweet chocolate chips
- 1/2 cup salted peanuts roughly chopped
- In the bowl of a stand mixer fitted with the paddle attachment or in a large bowl using a handheld electric mixer, beat the butter on medium speed until smooth and creamy.
- Add in the peanut butter and vanilla and beat until smooth, about 2 minutes.
- Next add in both sugars and beat until light and fluffy, scraping down the sides and bottom of the bowl as needed, about 2 minutes.
- Add in the eggs and yolk, one at a time, beating well after each addition. Turn mixer off.
- Add in the flour, oats, baking soda, baking powder, cinnamon, and salt. Whisk the ingredients together lightly before turning the mixer back on low and mixing in the dry ingredients until just combined. Be sure not to over mix here.
- Turn mixer off and use a spatula to fold in the M&Ms, chocolate chips, and peanuts.
- Cover the bowl and place it in the fridge for 30 minutes, or up to 2 days.
When ready to bake:
- Preheat oven to 350 degrees (F). Line two large baking sheets with parchment paper.
- Scoop two tablespoon sized mounds of dough onto the prepared cookie sheet, leaving a few inches between each cookies for spreading. Gently press down on each cookie ball, slightly flattening the ball. This will help them spread evenly in the oven. Sprinkle the top of each cookie with some extra oats, if desired.
- Bake one tray at a time, for 12 minutes, or until the edges are golden and the centers have set. If any edges spread out while baking, use a spatula and gently press them back in as soon as you remove the cookies from the oven.
- Cool cookies on the baking sheet for 10 minutes before transferring them to a cooling rack.