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Soft and Chewy Monster Cookies

Soft and Chewy Monster Cookies – Deliciously thick, soft and chewy peanut butter cookies stuffed full of oats, M&Ms, and chocolate chips!

Overhead shot of monster cookies with M&Ms on parchment paper.

Monster cookies are peanut butter cookies that have oats, M&Ms, and chocolate chips in them. Basically ALL my favourite cookie add-ins. Today I bring you my recipe for Monster Cookies.

They are super thick, soft, and chewy, and stuffed full of those delicious add-ins – just how they should be.

These cookies are so quick and easy to throw together and bake. No mixer required, and no chilling of the dough – just mix and bake!

Close-up of monster cookies with M&Ms on parchment paper.
Monster cookies with M&Ms on parchment paper.

How to make Soft and Chewy Monster Cookies

Ingredients you’ll need:

  • plain/all-purpose flour
  • porridge oats
  • baking powder
  • baking soda
  • salt
  • unsalted butter
  • caster/granulated sugar
  • light or dark brown sugar
  • large egg
  • vanilla extract
  • smooth peanut butter
  • chocolate M&M’s
  • chocolate chips

To make these cookies, simply whisk together the flour, oats, baking powder, baking soda, and salt. Set aside.

In a separate bowl, whisk together the butter and sugars until combined. Add the egg, vanilla, and peanut butter, and mix until combined.

Add the dry ingredients and mix until just combined, then fold in the M&Ms and chocolate chips.

Roll the dough into 1.5oz balls, place onto a baking tray lined with parchment paper or a silicone mat, and bake for 8 – 10 minutes. The cookies will be very soft, but will firm up as they cool.

Allow to cool on the baking tray for 5 – 10 minutes before transferring them to a wire rack to cool completely.

The printable recipe card with the FULL list of ingredients and instructions can be found at the bottom of this post.

NOTE: For best results, I highly recommend using the gram measurements (with a digital scale), rather than the cup measurements.

Cup measurements are simply not accurate enough, and I cannot guarantee the best results if you use them.

Side-view shot of thick monster cookies with M&Ms on parchment paper.
A tall stack of monster cookies with M&Ms on parchment paper.

These Soft and Chewy Monster Cookies are:

  • super quick and easy to make
  • loaded with peanut butter flavour
  • stuffed FULL of M&M’s and chocolate chips

How long will these Monster Cookies last? These cookies stay fresh kept in an airtight container, at room temperature for up to 1 week.

For freshly-baked cookies every time, you can keep the cookie dough balls in the fridge for up to 5 days, or in the freezer for up to 3 months. Bake straight from frozen!

If you try this recipe, let us know! Leave a comment, rate it, and don’t forget to tag me on Instagram and hashtag it #marshasbakingaddiction. I’d love to see!

A stack of monster cookies with M&Ms on parchment paper.
Stack of monster cookies with the top cookie broken in half.
Soft and Chewy Monster Cookies - Deliciously thick, soft and chewy peanut butter cookies stuffed full of oats, M&Ms, and chocolate chips! #peanutbutter #monstercookies #cookierecipes

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Stack of monster cookies with the top cookie broken in half.

Soft and Chewy Monster Cookies

Yield: 22 - 24 cookies
Prep Time: 10 minutes
Cook Time: 8 minutes
Total Time: 18 minutes

Deliciously thick, soft and chewy peanut butter cookies stuffed full of oats, M&Ms, and chocolate chips!

Ingredients

  • 1 and 1/2 cups (190g) plain/all-purpose flour
  • 1 cup (90g) porridge oats
  • 1 teaspoon baking powder
  • 1/2 teaspoon baking soda
  • 1/4 teaspoon salt
  • 1/2 cup (115g) unsalted butter, melted
  • 1/2 cup (100g) caster/granulated sugar
  • 1/4 cup (50g) light brown sugar
  • 1 large egg
  • 2 teaspoons vanilla extract
  • 1/2 cup (125g) smooth peanut butter
  • 3/4 cup (150g) M&Ms
  • 1/2 cup (90g) chocolate chips

Instructions

  1. Preheat the oven to 180C/350F/Gas 4, and line a baking tray with parchment paper, or a silicone mat. Set aside.
  2. Whisk together the flour, oats, baking powder, baking soda, and salt. Set aside.
  3. Whisk together the butter and sugars until combined. Add the egg, vanilla, and peanut butter, and mix until combined. Add the dry ingredients, and mix until just combined. Fold in the M&Ms and chocolate chips.
  4. Roll the dough into 1.5oz balls, place on the prepared baking tray, and bake for 8 - 10 minutes until barely browned around the edges. They will be very soft, but will firm up as they cool.
  5. Allow to cool on the baking tray for 5 - 10 minutes before transferring to a wire rack to cool completely.

Notes

Cookies stay fresh, kept in an airtight container, at room temperature for up to 1 week. Cookie dough balls can be kept in the fridge for up to 5 days, or frozen for up to 3 months. Bake straight from frozen.

Nutrition Information:
Yield: 24 cookies Serving Size: 1 cookie
Amount Per Serving: Calories: 170Total Fat: 9gSaturated Fat: 5gTrans Fat: 0gUnsaturated Fat: 4gCholesterol: 20mgSodium: 107mgCarbohydrates: 20gFiber: 1gSugar: 13gProtein: 3g

Nutrition information isn’t always accurate.

Did you make this recipe?

Tag @MarshasBakeBlog on Instagram and hashtag it #marshasbakingaddiction

janet wappel

Friday 27th of December 2019

What are porridge oats? Here in the States, it's either quick cooking or old fashioned (rolled) oats? Thank you!

Marsha

Friday 27th of December 2019

Porridge oats will be the quick oats. Although, if you prefer, you can use rolled oats instead.

Kelsey Renee | Blue Cheese Bungalow

Friday 28th of July 2017

These look so delicious! I am a sucker for m&m cookies! Pinning for later and following your accounts :)

Demeter | Beaming Baker

Thursday 20th of July 2017

These cookies look incredible, Marsha! But of course, everything you make looks wonderful. :) I'm thinking my nephew would love to go for an entire stack of these! Pinned, of course. Wishing you an awesome weekend ahead!

Marsha

Thursday 20th of July 2017

Thanks, Demeter! You, too! :) xo

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