There’s no mystery to the “monster” part. It’s the abundance that makes these cookies fun. They’re not spooky so much as loaded—and, with a glass of cold milk nearby, unusually easy to keep eating.

The Halloween batch gets its seasonal color from candy, but the recipe works year-round. The oat and peanut butter dough holds its mix-ins together without flour, while the centers stay soft and the edges turn lightly crisp.

What goes into the cookies

Eggs bind the dough and help it hold its shape. Creamy peanut butter supplies richness and structure; the recipe recommends Jif or Skippy instead of natural peanut butter. Light brown sugar keeps the middle moist, while granulated sugar helps the edges crisp. Vanilla rounds out the peanut butter and chocolate.

Old-fashioned rolled oats give the cookies their hearty chew. Use certified gluten-free oats if that matters for your needs. Baking soda helps the cookies rise and spread, and kosher salt keeps the sweetness in check while sharpening the peanut butter flavor.

Mini semisweet chocolate chips spread chocolate through the dough without taking it over. Reese’s Pieces bring crunch and more peanut butter flavor; M&M’s are another option. Flaky sea salt is optional, but a little on top cuts through the sweetness.

Mixing the dough

Begin by whisking the eggs until blended and lightly frothy. Add the peanut butter, both sugars and vanilla; whisk as far as the mixture allows, then use a sturdy spatula to finish stirring until the dough looks thick, smooth and glossy.

Fold in the oats, baking soda and salt until the oats are evenly coated. Then stir in the chocolate chips and candies to distribute the mix-ins throughout.

Shape the cookies, then trust the oven

Fold in the mini semisweet chocolate chips and Reese’s Pieces until they’re distributed through the dough. Chill it for about 20 minutes; that gives the oats a chance to take up moisture and helps the cookies hold their shape. Scoop generous two-tablespoon portions onto parchment-lined baking sheets. Add a few candies and chips on top of each mound. It’s a small step, but it gives the finished cookies their unmistakable monster-cookie look. Bake for 10 to 12 minutes, stopping when the edges have set and the centers still seem a little underdone. They’ll firm up on the hot pan, so waiting for fully baked-looking centers is the quickest route to a drier cookie.

While they’re still warm, finish with a little flaky sea salt. Leave the cookies on the baking sheet for at least 10 minutes. They’ll look very soft at first; cooling is what brings them to a thick, chewy texture with peanut butter at the center of the flavor.

Change the candy, keep the dough

The recipe doesn’t need a seasonal overhaul. Swap the candy colors to suit the occasion: orange, purple, and black for Halloween; red and green M&M’s or Reese’s Pieces for Christmas; pastels for spring; or red, pink, and white for Valentine’s Day. And if it’s an ordinary Tuesday, whatever chocolate-coated candy is in the pantry will do.

One-Bowl Monster Cookies

These cookies are forgiving, but the peanut butter matters. Use conventional creamy peanut butter such as Jif or Skippy; natural varieties can separate and make the cookies spread unpredictably. For a gluten-free batch, choose certified gluten-free rolled oats and check the labels on the chocolate chips and candies. Heat the oven to 350°F, with racks in the upper third and center, and line two baking sheets with parchment. Whisk the eggs until blended and lightly frothy. Stir in the peanut butter, brown sugar, granulated sugar, and vanilla until the mixture is smooth and glossy. Add the oats, baking soda, and salt, then fold in mini chocolate chips and Reese’s Pieces. Chill the sticky dough for 20 minutes so the oats can absorb moisture and help the cookies hold their shape. Scoop generous 2-tablespoon portions onto the baking sheets, spacing them about 2 inches apart. A cookie scoop makes the job easier. Press a few extra candies and chips into each top. Bake for 10 to 12 minutes, rotating the pans halfway through. Pull them when the edges have set but the centers still look a little soft. That’s the key: the cookies keep cooking as they cool, and waiting for firm centers in the oven risks losing their chew. Add flaky sea salt while they’re warm, if you like, and leave them on the sheet for at least 10 minutes before moving them to a rack. They’ll be soft at first, then settle into chewy, peanut buttery cookies. Store them in an airtight container at room temperature for up to four days. You can also freeze scooped portions and bake them straight from frozen, adding a minute or two.

FAQs

You don’t need a mixer or a separate flour measurement for these cookies. The dough comes together in one bowl with a spoon; give it a brief chill, then let the soft centers finish setting as the cookies cool. **Can I use natural peanut butter?** It’s not the best choice here. Because it can separate, natural peanut butter may cause unpredictable spreading. Conventional creamy peanut butter is more reliable. **Can I freeze the dough?** Yes. Freeze individual scoops until firm, transfer them to a freezer bag, and bake from frozen with an extra minute or two in the oven.

More Cookies to Try

- [Easy 4-Ingredient Peanut Butter Cookies](https://joythebaker.com/2022/01/easy-4-ingredient-peanut-butter-cookies/): another flourless cookie option. - [Blueberry Cobbler Thumbprint Cookies](https://joythebaker.com/2018/09/blueberry-cobbler-thumbprint-cookies/): a jam-filled treat that pairs well with coffee. - [Confetti Holiday Shortbread](https://joythebaker.com/2018/12/confetti-holiday-shortbread/): an easy cookie to adapt for the holidays.