Monster Mash Cookies

A little peanut butter, a little oatmeal, a whole lot of chocolate, and enough Halloween candy to make your cookie jar look like it got into the trick-or-treat bag.

These Monster Mash Cookies are exactly what I want a Halloween cookie to be: big, chunky, chewy, colorful, and slightly chaotic in the best possible way.

The base starts with a soft peanut butter oatmeal cookie loaded with butterscotch chips, Halloween M&M's, and crushed green KitKats. Then we pile a little extra dough on top before baking to get those tall, bakery-style cookies.

They're not meant to be dainty.

They're meant to be MONSTER cookies.

Why You'll Love These Cookies

• Thick and chunky bakery-style cookies

• Chewy oatmeal and creamy peanut butter

• Loaded with Halloween candy

• Butterscotch adds a warm, caramel-like sweetness

• Green KitKat pieces add extra crunch and fun

• Perfect for Halloween parties and spooky-season baking

• Easy to customize with whatever Halloween candy you have hiding in the pantry

Ingredients

For the Cookies

• 1 cup salted butter, softened

• 1 cup brown sugar

• ½ cup granulated sugar

• ½ cup creamy peanut butter

• 2 eggs

• 1 tablespoon vanilla extract

• 1 cup all-purpose flour

• 1 cup cake flour

• ¾ teaspoon baking soda

• ½ teaspoon cornstarch

• ¾ teaspoon salt

• 2 ½ cups old-fashioned rolled oats

• ½ cup butterscotch chips

• 1 cup Halloween M&M's

• ½ cup crushed green Halloween mini KitKats

Don't forget: you'll find the full measurements and recipe instructions in the recipe card below.

What Makes These "Monster" Cookies?

It's really the chunks.

I don't just scoop these cookies and call it a day. After portioning the dough, I use the extra dough to build up the tops of each cookie. I literally grab pieces with my hands and pile them onto the dough balls.

The result?

Tall, chunky, bakery-style cookies with plenty of texture. They're supposed to look a little wild. That's the whole point.

Why Old-Fashioned Oats?

Definitely reach for old-fashioned rolled oats instead of instant oats for this recipe.

The larger oats give the cookies more chew and texture, which works especially well with the peanut butter and all those candy mix-ins.

Plus, we're already going over the top with the candy. We might as well make the cookie itself interesting too.

My Best Tips for Monster Cookies

Build Up Those Cookies

Don't level your cookie scoop. Use the extra dough to create a taller, chunky mound on top. This helps give you that thick bakery-style look.

Don't Overmix

Once the flour is incorporated, stop mixing. You want a thick dough with plenty of room for all those oats and candy pieces.

Refrigerate the Dough

A quick 30–60 minute chill helps the cookies hold their shape and stay nice and thick while baking.

You can even refrigerate them for up to 24 hours. Just let the dough sit at room temperature for about 30 minutes before baking.

Save Some Candy for the Top

If you want those colorful Halloween M&M's and KitKat pieces to really stand out, press a few extra pieces onto the tops before chilling.

Because if we're making Halloween cookies, we want people to know they're Halloween cookies.

Don't Overbake

Take them out when the edges are golden but the centers still look soft.

They'll continue setting as they cool, giving you that chewy middle we're after.

Make Them Your Own

This is one of those recipes where you can have a little fun.

Don't have green KitKats? Try another Halloween candy.

You could add:

• Reese's Pieces

• Peanut butter chips

• Chocolate chunks

• Halloween sprinkles

• Chopped candy bars

• White chocolate chips

• Different colors of M&M's

The monster doesn't have to look the same every time.

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Storage

Store completely cooled cookies in an airtight container at room temperature for several days.

You can also freeze the baked cookies or freeze the portioned dough for later. Just make sure the dough is well wrapped before freezing.

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