These monster cookies are chewy and slightly dense — a peanut-butter-and-oats base studded with plain M&M’s and semi-sweet chocolate chips for pockets of color and chocolate. The texture is tender in the center with a lightly golden edge, so they hold their chunky shape instead of spreading thin.
They come together quickly but require a short chill: refrigerate the dough at least 1 hour, then bake small, heaped 1-tablespoon cookies about 12 minutes. Makes 24 cookies — perfect for Halloween treats, bake sales, or a crowd-pleasing snack.
Why You’ll Love These Cookies
A few reasons these monster cookies are a weekday-friendly crowd-pleaser:
Yield is about 24 small cookies when portioned as directed; increase portion size and bake time for giant cookies.
Ingredients You’ll Need
How to Make Monster Cookies
- Cream the butter and brown sugar: In a large mixing bowl, cream 1/2 cup butter and 3/4 cup light brown sugar (firmly packed) for about 4 minutes, until the mixture is creamy and pale. This aerates the sugar and butter so the cookies have a pleasant texture.
- Add flavorings and egg: Beat in 1 tsp vanilla extract, then add 1 large egg and mix until smooth. Finish by mixing in 3/4 cup creamy peanut butter until evenly combined.
- Combine dry ingredients: In a separate bowl, sift or whisk together 1/2 cup all-purpose flour, 1/2 tsp baking soda, and 1 tsp cornstarch so the leavening and cornstarch are evenly distributed.
- Fold dry into wet: Add the dry mixture to the peanut-butter mixture and gently fold until just combined. Avoid overmixing to keep the cookies tender.
- Stir in oats and mix-ins: Fold in 1 cup rolled oats, 1/2 cup plain M&Ms, and 1/2 cup semi-sweet chocolate chips until evenly distributed through the dough.
- Chill the dough: Cover the bowl with plastic wrap and refrigerate the dough for at least 1 hour. Chilling firms the dough so the cookies hold their chunky shape and develop chew.
- Prepare to bake: Line two baking trays with parchment paper and preheat the oven to 350 F.
- Portion the cookies: Remove the chilled dough — it will be slightly sticky but firm enough to handle. Scoop balls of approximately 1 heaped tablespoon and place them on the prepared trays, spacing them apart. Flatten each ball slightly with your hand or a spatula, and press a few extra M&M’s or chips on top if desired.
- Bake until edges are golden: Bake the cookies for approximately 12 minutes, or until the edges are golden brown while the centers remain slightly soft. The cookies will set as they cool.
- Cool gently: Let the cookies cool briefly on the tray, then transfer them to a wire rack to cool completely so they finish firming up without overbaking.
Chill Dough for Shape
Chilling is the single most important step for these cookies. The dough firms as it chills, which prevents excessive spreading and concentrates the peanut-butter flavor for a chewier interior.
If you’re short on time, a 30-minute chill will help, but the recipe’s 1 hour minimum gives the best hold and texture.
- Refrigerate in a covered bowl so the dough doesn’t dry out.
- If you prefer slightly taller cookies, chill for 2 hours or overnight.
- Warm dough will spread thin and lose the chunky ‘monster’ look.
Portioning & Bake Time
Portion about 1 heaped tablespoon per cookie for the recipe’s quoted yield of 24; larger portions will require a longer bake time and will produce fewer cookies. For a giant, shareable cookie variation, try the Deep Dish Monster Cookies recipe linked here for inspiration.
Flatten each ball slightly before baking — these cookies don’t spread as much as a classic drop cookie, so the pre-flattening helps them bake to the right thickness.
- Small (1 Tbsp) cookies ≈ 12 minutes at 350 F.
- If making 2–3 Tbsp cookie mounds, add 3–5 minutes and watch for golden edges.
- Rotate pans halfway through baking for even color and doneness.
Freezing & Storage
Store baked cookies covered in an airtight container at room temperature for about 3 days. For longer keeping, freeze fully cooled cookies for up to 3 months.
Freeze dough balls on a tray until firm, then transfer to a sealed bag to bake from frozen — add a couple of minutes to the bake time.
- To refresh frozen cookies, thaw at room temperature 20–30 minutes and warm in a 300 F oven for 5–7 minutes to revive the just-baked texture.
- Layer cookies with parchment in the container to prevent sticking and preserve decoration.
Tips for Success
Chill time matters: Do not skip the 1-hour chill—cold dough spreads less and produces the dense, chewy texture these cookies are known for.
Portion consistently: Use a small cookie scoop or measure roughly 1 heaped tablespoon per cookie to get the stated yield of 24 and predictable bake times.
Don’t overbake: Remove the cookies when the edges are golden and the centers still look a bit soft; carryover heat will finish them without drying them out.
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More Monster Treats
Frequently Asked Questions
Final Notes
These monster cookies are built for texture and convenience: mix, chill, and bake for reliably chewy, candy-studded cookies that travel well to parties and school events.
If you want more ways to play with the dough — from dipable cookie dough to stuffed or gluten-free options — check the related recipes in the “More Monster Treats” list above.
Monster Cookie Recipe
Equipment
- large mixing bowl
- sifter
- baking trays
- parchment paper
- wire rack
Ingredients
- 1/2 cup butter softened
- 3/4 cup light brown sugar firmly packed (dark also works)
- 1 tsp vanilla extract
- 1 large large egg
- 3/4 cup creamy peanut butter
- 1/2 cup all-purpose flour
- 1/2 tsp baking soda
- 1 tsp cornstarch
- 1 cup rolled oats
- 1/2 cup plain M&Ms
- 1/2 cup semi-sweet chocolate chips
Instructions
- In a large mixing bowl, cream 1/2 cup butter and 3/4 cup light brown sugar (firmly packed) for about 4 minutes, until creamy and pale. Add 1 tsp vanilla extract and beat briefly, then add 1 large egg and beat until smooth. Add 3/4 cups creamy peanut butter and beat until combined.
- In a separate bowl, sift 1/2 cup all-purpose flour, 1/2 tsp baking soda, and 1 tsp cornstarch, then gently whisk together. Add the dry ingredients to the wet mixture and gently fold to combine. Stir in 1 cup rolled oats, 1/2 cup plain M&Ms, and 1/2 cup semi-sweet chocolate chips until evenly distributed.
- Cover the bowl with plastic wrap and refrigerate the dough for at least 1 hour to firm up so the cookies hold their shape.
- Line two baking trays with parchment paper and preheat the oven to 350 F.
- Remove the chilled dough from the fridge; it will be slightly sticky but firm enough to roll into balls by hand.
- Portion the dough into balls of approximately 1 heaped tablespoon and place them on the prepared trays, spacing them apart. Flatten each ball slightly with your hand or a spatula, and press a few extra M&M’s or chocolate chips on top if desired.
- Bake the cookies for approximately 12 minutes, or until the edges are golden brown. Let the cookies cool slightly on the tray before transferring them to a wire rack to cool completely.
