Monster Cookies

Monster Cookies are thick, chewy cookies filled to the brim with peanut butter, oats, chocolate chips and M&M’s. Some might even call them, monstrous!

monster cookies

Katie, what on Earth is a Monster Cookie? I hear you people, I had no idea either until I saw these bad boys popping up all over Pinterest a few years ago. Obviously, I’m cookie obsessed so I had to know. Curiously I clicked on a few links and discovered they were a beautiful marriage between a chocolate chip and my beloved oatmeal cookies with a healthy dose of peanut butter and chocolate thrown in for good measure. I was hooked. I’ve made them hundreds of times over the years but realised I’d never blogged my version of these beauties. Well, here they are!

monster cookies

Wanna know what makes these cookies even better? You don’t need to go through the rigmarole of chilling the dough. Hell yes, no waiting around! That means, if you’re quick, you could be eating freshly baked cookies within the hour.

If you’re anything like me you’ll already have all the ingredients for these cookies in your store cupboard but if you find yourself short you can always make a few substitutions. If you’ve got Reeses Pieces languishing away in your cupboard, lash them in there in place of the M&M’s. Or, you could even bash up some Mini Eggs leftover from Easter (I know, who am I kidding?!). Candy is candy, it all tastes good!

monster cookies

As always I’ve added some instructions on freezing your cookies in the tips section of the recipe below, because at this point I’m sure you’re all well aware that I’m a huge fan of the freezer cookie.

If you’re looking for a little more cookie inspiration to get you through this Lockdown situation, look no further:

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Monster Cookies

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5 from 16 reviews


Monster Cookies are thick, chewy cookies filled to the brim with peanut butter, oats, chocolate chips and M&M’s. Some might even call them, monstrous!


Units Scale
  • 120g unsalted butter, softened
  • 100g caster sugar
  • 100g light brown sugar
  • 125g peanut butter, smooth or chunky
  • 1 large, free range egg
  • 1 teaspoon vanilla extract
  • 125g plain flour
  • 125g rolled oats
  • 1/4 teaspoon salt
  • 1/2 teaspoon baking powder
  • 1/2 teaspoon bicarbonate of soda
  • 150g chocolate M&Ms
  • 100g chocolate chips


  1. Preheat oven to 175C and line 2 large cookies sheets with baking parchment. Set aside.
  2. In the bowl of an electric mixer cream the butter and sugars together until light and fluffy, around 5 minutes.
  3. Add the peanut butter to the butter and sugar and mix until combined. Add in the egg and vanilla and mix.
  4. In a separate mixing bowl stir together the flour, oats, salt, baking powder and bicarb.  Add the dry ingredients to the wet and mix until just combined. Stir the chocolate chips and M&Ms by hand until evenly distributed.
  5. Roll tablespoons of the cookie dough into little balls and place onto your prepared baking sheets leaving around 1.5″ between each cookie to allow for spreading.
  6. Bake for 10-12 minutes until just set and slightly golden around the edges.
  7. Allow to cool for 10 minutes before transferring the cookies to a wire rack to cool completely.


Cookies can be kept for up to 5 days in an air-proof container.

To freeze the cookie dough make up to step 5, place the prepared baking sheets into the freezer for 1 hour before placing the frozen cookies in a ziplock bag. Frozen cookies can be stored for up to 3 month. Bake from frozen adding 2 minutes to the baking time.

If you want your cookies to look like the ones in the photos, poke a few extra M&Ms and chocolate chips into the cookie dough balls just before baking.

  • Prep Time: 20 minutes
  • Cook Time: 12 minutes
  • Category: cookies
  • Cuisine: American


  1. April 15, 2020 / 5:09 pm

    I think this is the best cookie ever. It has everything in there that I like.

  2. April 15, 2020 / 5:27 pm

    Ooh ive printed this off to use and I can switch out the M&M’s to left over mini creme eggs or mini eggs maybe… youve got me thinking now x

    • April 15, 2020 / 5:42 pm

      They would be pure filth with mini creme eggs, I like your thinking!!

      Katie xoxo

  3. April 15, 2020 / 5:28 pm

    We love baking cookies. These sound great with a generous helping of peanut butter mixed in.

  4. April 16, 2020 / 4:51 pm

    These cookies are so bright and colorful, but most of all they’re soft! I love a soft chocolate chip cookie!

  5. April 17, 2020 / 9:57 am

    OH WOW! I could be very tempted to make these! Might add the ingredients to my shopping list… chocolate is essential right?

  6. April 17, 2020 / 10:41 am

    These look very impressive! Just pinned them as I’m starting to get back into baking again whilst we are under lockdown. I think my housemates would adore me if I made these for them!

  7. April 17, 2020 / 10:44 am

    I can’t even tell you how much I needed this reciepe in my life! These actually look amazing, and I am no baker but I can manage cookies.

    Thank you so much for sharing, these are perfect for a self isolation activity!

  8. April 17, 2020 / 1:59 pm

    Spookily enough I was just talking yesterday that I need to make cookies soon, am definitely going to be trying these x

    April 17, 2020 / 4:32 pm

    I’ve been talking about doing more baking with the girls. We made a cake just the other day and now by chance they want to make cookies. These sound like they would be perfect. We love cookies, chocolate and peanut butter so they are ideal for us!

  10. April 17, 2020 / 5:18 pm

    Cookies are my absolute faves! I really love choc chip and these look so colourful and delicious! I will have to give this a go along with at least half of the other cookie recipes too!

  11. Valerie
    April 18, 2020 / 1:07 am

    I love freshly baked chewy cookies, particularly chocolate chip. My oldest loves chocolate and peanut butter, as does hubby. These would not last long at my house at all.

  12. Rhian westbury
    April 18, 2020 / 1:45 pm

    Wow they really are monsters, so much packed inside them. I love anything with peanut butter in so these sound very tasty x

  13. April 18, 2020 / 2:31 pm

    These cookies wouldn’t last five minutes in my house! We’ve been making a lot of cookies and cakes in the house recently so might just have to give these a go too!

  14. April 18, 2020 / 9:38 pm

    For me the bigger the cookies, the better!!! Love all that chocolaty goodness in every bite!

  15. April 18, 2020 / 10:52 pm

    I love loaded cookies and these are no exception! I can’t wait to make them! Have you tried them with peanut butter M&Ms? I’m curious how it would taste with them!

  16. April 19, 2020 / 3:13 am

    These were so fun to make with two bored kids! We loved how we could just pack them with chocolate goodies!

  17. April 19, 2020 / 4:35 am

    Who doesn’t love this flavor of cookies, it’s so delicious and I am sure no one can resist himself or herself of eating these cookies. THE BEST!

  18. April 19, 2020 / 7:41 am

    Wow these sound so good! I can’t wait to try this cookie recipe out soon!

  19. Hannah
    April 19, 2020 / 12:23 pm

    I want some of these right now. I love M&Ms too. I’ve had them a few years ago on cookies and they taste amazing

  20. Alisa Infanti
    April 19, 2020 / 7:16 pm

    My kids loved making this recipe today. So much fun and they were delicious! Time for another batch!

  21. April 20, 2020 / 8:19 am

    I stumbled across these cookies and my god I want to eat them now. They look delicious. Your photography is stunning too

  22. April 20, 2020 / 2:34 pm

    what a fun cookie recipe! Love the colours too! Have to try it out soon!

  23. April 20, 2020 / 3:09 pm

    I have not heard of monster cookies but they look and sound delicious

  24. Alexis
    April 20, 2020 / 7:55 pm

    These are one of my children’s favorite cookies. We’ve enjoyed this recipe quite a bit while baking during our quarantine.

  25. April 22, 2020 / 4:41 am

    Wow, monster cookies! These look so perfect and delicious. Thanks for the detailed recipe.

  26. April 22, 2020 / 5:51 pm

    These must be the cutest cookies ever. I love peanut butter too so bookmarking these to make

  27. April 22, 2020 / 10:28 pm

    These Monster cookies look fabulous. The chunky and chewy texture is what I love in cookies.

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