Giant Monster Cookies

These Giant Monster Cookies are full of chocolate peanut buttery deliciousness! They’re one of the easiest cookies you’ll ever make.

Monster Cookies

What Are Giant Monster Cookies?

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

Giant Monster Cookie Tips & Trick

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

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.

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

Giant Monster Cookies

Giant Monster Cookies with M&Ms

  • Prep Time: 1h 10m
  • Cook Time: 30m
  • Total Time: 1h 40m
  • Yield: 9 cookies


Monster Cookie Recipe

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


  1. Preheat oven to 350°F.
  2. Place oats on baking sheet and toast for 12 minutes, rotating pan halfway through. Remove and let cool on cooling rack.
  3. Combine oats, baking powder, baking soda, flour, salt, and cinnamon in medium bowl. Set aside.
  4. Combine butter, sugar, brown sugar, and peanut butter in bowl of mixer until fully mixed, about three minutes at medium speed.
  5. Add eggs, one at a time, mixing for 30 seconds after each addition.
  6. Add vanilla extract.
  7. Reduce mixer speed and add oat mixture. Mix just until combined.
  8. Add 1/2 cup M&Ms and 1/2 cup chocolate chips.
  9. Cover bowl with plastic wrap and let rest at room temperature for one hour.
  10. Preheat oven to 350°F.
  11. Use 1/2 cup measuring cup to portion cookies and place on parchment-lined baking sheet. Cover individual cookies with remaining M&M's.
  12. Bake for 16-20 minutes or until edges are slightly golden brown. Remove from oven and let cool.

This recipe was developed and written by Rebecca Swanner of Let’s Eat Cake. Check out her site for more fun and easy baking recipes!

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anna williamson

Cookies !

Kari Uzzle

My dough seems very dry and crumbly, what would be the cause of that?

Marie gaetano

Kindly confirm the volume measurement and gram weight of the oaTs. i am unable to find a source indicating that 1 cup = 150 grams (therefore, 2 cups would be 300 grams). Id like to try the recipe, but the amount of oats (cups equal to grams stated) seems incongruent. Please help clarify. Thank you!