These monster cookies combine peanut butter, chocolate chips, oatmeal and M&Ms. They bake up soft, chewy, full of texture, and pleasantly oversized. Thick, flavorful, and crowd-pleasing for both kids and adults.
Note: This recipe was updated November 3, 2022 with new photos, recipe tips and a slightly revised ingredient list.
Monster cookies are the best of several cookie worlds: oatmeal, peanut butter, M&M and chocolate chip all in one bite. They have a satisfyingly chewy texture and a rich peanut butter flavor that pairs perfectly with chocolate. This recipe makes thick cookies that hold plenty of mix-ins, yet remain soft inside.
One of the conveniences of this recipe is that the dough does not require chilling, though you can freeze formed dough balls to bake later.
Monster Cookie Recipe
The core elements of these monster cookies are peanut butter, oats, chocolate chips and M&Ms. Below are clear steps and helpful tips to guide you through the process.
- Preheat the oven to 350°F (180°C; 170°C for convection). Line cookie sheets with parchment paper or silicone baking mats. If you plan to freeze dough balls, lining pans is optional for that step.
- In a large bowl, beat together softened butter, brown sugar, granulated sugar and peanut butter until smooth. The butter should be softened but not melted. Using equal amounts of butter and peanut butter gives the best balance of flavor and texture.
- Mix in the egg and vanilla extract. For best results, use an egg at room temperature.
- Turn off the mixer and add the flour, cornstarch, baking powder, baking soda and salt. Stir a few times by hand to prevent dry ingredients from flying, then mix on low speed until just combined.
- Fold in the oats. Old-fashioned rolled oats (large rolled oats) are recommended for the best texture; quick oats will work but give a different result.
- Stir in the chocolate chips and M&Ms. You can use regular or mini M&Ms depending on preference.
- Form the dough into balls. A cookie scoop prevents sticky hands and yields even cookies. For large cookies use about 3 tablespoons of dough (two 1.5-tablespoon scoops).
- Place dough balls 2–3 inches apart on the lined sheets and bake one sheet at a time for 10–12 minutes, or until the tops look set. When cookies come out of the oven, press a few extra chocolate chips or M&Ms on top for an attractive finish.
Note: If making smaller cookies (about 1.5 tablespoons each), bake for 8–10 minutes.
Freezing the Dough
You can freeze the dough balls for convenience. Form the dough into balls, place them in a freezer bag, remove excess air, and freeze for up to 2 months. Bake from frozen and add an extra 1–2 minutes to the bake time.
These monster cookies deliver the perfect combination of peanut butter, chocolate and chewy cookie texture. They’re easy to make and endlessly satisfying—grab a cold glass of milk and enjoy.
If you enjoy these monster cookies, you might also like other peanut butter and oatmeal cookie variations.
Soft and Chewy Monster Cookies
Equipment
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Cookie sheets
Ingredients
- 1/2 cup unsalted butter (112 grams), softened
- 1/2 cup brown sugar (100 grams)
- 1/3 cup granulated sugar (66 grams)
- 1/2 cup peanut butter (130 grams)
- 1 large egg
- 1 teaspoon vanilla extract
- 3/4 cup plus 2 tablespoons all-purpose flour (109 grams)
- 1 tablespoon cornstarch
- 1/2 teaspoon baking soda
- 1/2 teaspoon baking powder
- 1/4 teaspoon salt
- 1 cup old-fashioned oats (90 grams)
- 1/2 cup chocolate chips (95 grams), plus more for the tops
- 1/2 cup M&Ms (about 100 grams), plus more for the tops
Instructions
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Preheat oven to 350°F and line cookie sheets with parchment or silicone mats.
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Beat butter, brown sugar, granulated sugar and peanut butter together in a large bowl until smooth.
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Mix in the egg and vanilla extract until incorporated.
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Add flour, cornstarch, baking powder, baking soda and salt. Stir a few times by hand, then mix on low until combined.
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Stir in the oats.
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Fold in the chocolate chips and M&Ms.
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Form dough into balls about 3 tablespoons each and place 2–3 inches apart on the prepared sheets.
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Bake one sheet at a time for 11–13 minutes, or until tops look set. Cool on the tray for at least 10 minutes before transferring to a wire rack. While still warm, press extra chocolate chips or M&Ms on top if desired.
Notes
- Peanut butter: Use smooth, commercial peanut butter rather than natural or homemade varieties; oil separation in natural peanut butter can change the cookie texture.
- Oats: Use old-fashioned rolled oats for the best texture. Avoid steel-cut oats and instant or finely ground oats.
- M&Ms: Regular or mini both work well—choose your preference.
- Storage: Store cookies in an airtight container at room temperature for up to four days.
- Nutrition: Nutrition facts are estimates based on one cookie when the recipe yields 16 cookies.