Making your favorite cookie in a GIANT version just seems like the right thing to do. 😉 We are a huge fan of Monster Cookies and absolutely can’t get enough of this extra big version! Hope you love Giant Monster Cookies as much as we do! Looking for more Cookie Recipes?  Try my Sugar Cookie Recipe and highly rated Snickerdoodles!

Monster Cookies on White Plate

Monster Cookies Recipe

Why do we call these monster cookies? Well, I have a few ideas.

  1. At least as far as this recipe goes, these giant monster cookies are monstrous in size! Each cookie uses 1/2 cup of monster cookie batter and bakes into a cookie that is bigger than your palm.
  2. Since monster cookies are essentially a cross between two of America’s favorite cookies – the oatmeal cookie and the peanut butter cookie – if you spot someone eating one, your green-eyed jealousy monster is likely to say hi!
  3. This cookie recipe is so easy that even a monster could make them! And, while it does make it a little bit easier to make them in a stand mixer, you definitely don’t need to own one to make this monster cookie recipe!
  4. The M&Ms make them look a little bit like monsters. If monsters looked like cookies, that is.

Giant Monster Cookies stacked on White Plate

Monster Cookie Tips & Tricks

When making these giant monster cookies, here a few tips you may find:

  • Toast the oats! Toasting the oats brings out their flavor a little bit more against the peanut butter. If you don’t like the flavor of oats, but just prefer their texture, don’t toast them.
  • Let the batter sit for an hour at room temperature. You don’t have to do this, but letting the batter sit, you hydrate the oats, which I found resulted in a better texture when baked.
  • When you remove these from the oven, you may notice the giant monster cookies won’t look totally baked. They’ll continue baking a little on the cookie sheet. It is important not to overbake these cookies!
  • This one is optional but add a little spice. I added 1/2 teaspoon of cinnamon to add a bit more complexity to the flavor of the final cookie.

Monster Cookie Recipe Stacked and Top Cookie Broken in Half

How long do you cook Giant Monster Cookies? The monster cookies bake for 16-20 minutes at 350°F. Remove them when they are light golden brown on the edges.

Can I make smaller Monster Cookies? You can! The giant monster cookies use a 1/2 cup of batter per cookie, but you can size them down to 1/4 cup or 2 Tablespoons for smaller monsters. You will have to reduce the cooking time. I also have a recipe for Soft Batch Monster Cookies you might love.

Can I customize my Giant Monster Cookies? Absolutely. Swap the chocolate chips for peanut butter chips for even more peanut butter flavor or customize the M&Ms for the holiday! Red and Green for Christmas; pink, red, and white for Valentine’s Day; or pastels for Easter. I like to add more M&Ms on top to make them even super decorative.

Can Giant Monster Cookies be gluten-free? I believe they can, but I haven’t yet tested it. If you use gluten-free oats and substitute the flour for 1:1 flour, the recipe should work. This will change the texture slightly.

Giant Monster Cookie Recipe On Cooling Rack

Giant Monster Cookies with M&Ms
4.75 from 12 votes

Giant Monster Cookies

Prep Time 1 hr 10 mins
Cook Time 30 mins
Total Time 1 hr 40 mins


  • 2 cups (300g) oats, preferably not quick oats
  • 1/4 tsp. baking powder
  • 1 tsp. baking soda
  • 1 cup (128g) all-purpose flour
  • 1/4 tsp. coarse kosher salt
  • 1/2 tsp. ground cinnamon optional
  • 1/2 cup (113g) unsalted butter, softened
  • 1/4 cup (57g) granulated sugar
  • 3/4 cup (150g) brown sugar, packed
  • 1 cup (226g) creamy peanut butter
  • 2 tsp. vanilla extract
  • 2 large eggs, room temperature
  • 1 cup M&Ms, divided (mini M&M's work great as garnish as well)
  • 1/2 cup chocolate chips


Toasting the Oats (Optional)

  • Preheat oven to 350°F.
  • Place oats on baking sheet and toast for 12 minutes, rotating pan halfway through. Remove and let cool on cooling rack.

Monster Cookie

  • Combine oats, baking powder, baking soda, flour, salt, and cinnamon in medium bowl. Set aside.
  • Combine butter, sugar, brown sugar, and peanut butter in bowl of mixer until fully mixed, about three minutes at medium speed.
  • Add eggs, one at a time, mixing for 30 seconds after each addition.
  • Add vanilla extract.
  • Reduce mixer speed and add oat mixture. Mix just until combined.
  • Add 1/2 cup M&Ms and 1/2 cup chocolate chips.
  • Cover bowl with plastic wrap and let rest at room temperature for one hour.
  • Preheat oven to 350°F.
  • Use 1/2 cup measuring cup to portion cookies and place on parchment-lined baking sheet. Cover individual cookies with remaining M&M's.
  • Bake for 16-20 minutes or until edges are slightly golden brown. Remove from oven and let cool.

Did you make this recipe?

Thank you for making my recipe! You took pictures, right? Well go ahead and post them on Instagram! Be sure to mention me @iambaker and use the hashtag #YouAreBaker.

Photos, some copy, and recipe are from Rebecca Swanner of Let’s Eat Cake!


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Meet Amanda Rettke

Amanda Rettke is the creator of I Am Baker, and the bestselling author of Surprise Inside Cakes: Amazing Cakes for Every Occasion – With a Little Something Extra Inside.Over the course of her 15+ year blogging adventure, she has been featured in and collaborated with the Food Network, New York Times, LA Times, Country Living Magazine, People Magazine, Epicurious, Brides, Romantic Homes, life:beautiful, Publishers Weekly, The Daily Mail, Star Tribune, The Globe and Mail, DailyCandy, YumSugar, The Knot, The Kitchn, and Parade, to name a few.

Reader Comments

  1. I love your recipes – I have been thrilled with everything I have made from
    I have also shared with friends who enjoyed the recipes, as well! Thank you!

  2. The Monster Cookies are now sitting at room temperature – soon to be baked! 🤞🎉 🍪
    I’m going to make the smaller cookies – I’m glad I read the responses/suggestions with these cookies! Yum! Best recipes ever! Thank you!

  3. So you know, this can easily be converted to gluten free. Use a cup of oat flour in place. Easy to do by blender

  4. Could you help me please I made the cookie dough but it was all crumbley what did I do wrong thanks for any help. Carrol

  5. Absolutely delicious!! I followed the recipe exactly as I do when trying any new recipe. I won’t be changing a thing! They were wonderful and my family loved them! Thank you!!

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