If you prefer a classic holiday cookie, try these Peanut Butter Oatmeal Monster Cookies. Rolled oats, creamy peanut butter, and M&Ms combine for a chocolatey, nutty treat that’s easy to love and perfect for cookie swaps or a festive platter.
About these Cookies
Monster cookies are a Midwestern favorite made from peanut butter, oats, and M&Ms. They’re hearty, colorful, and very popular during the holidays. The combination of chewy oats, rich peanut butter, and crunchy candy pieces gives these cookies a satisfying texture and flavor.
This recipe is flexible—add chopped pretzels, marshmallows, chopped candy bars, or extra chocolate chips to make them your own.
Recipe Ingredients
- Old fashioned oats (quick oats are too soft for this recipe)
- Brown sugar and white sugar
- Peanut butter (or substitute another nut/seed butter if desired)
- All-purpose flour (or a 1:1 gluten-free flour)
- Cornstarch (for tender texture)
- M&Ms (classic mix-in for monster cookies)
See the recipe card below for exact measurements.
How to Make This Recipe
1. In a mixing bowl, cream together softened butter, peanut butter, brown sugar, and white sugar.
2. Beat in the eggs, vanilla, and water until combined.
3. Fold in the flour, cornstarch, baking soda, and salt.
4. Stir in the old fashioned oats and M&Ms. Combine, then refrigerate the dough for 20 minutes. While chilling, preheat the oven to 350°F (175°C).
5. After chilling, use a cookie scoop to portion dough onto a parchment-lined baking sheet.
6. Bake 12–15 minutes or until the edges are golden. Remove from the oven, transfer to a wire rack (or slide the parchment off the baking sheet) to cool, and enjoy.
Storing and Freezing
Store cookies in an airtight container at room temperature, or refrigerate if you prefer a chewier, chilled cookie. Place a slice of bread in the container to help keep cookies soft—replace the bread as it dries.
Freezing options:
- Unbaked dough: Scoop and freeze balls on a baking sheet until solid, then transfer to an airtight container or freezer bag. Bake from frozen, adding 2–3 minutes to the baking time.
- Baked cookies: Cool completely, then layer with parchment between stacks in a freezer-safe container or bag.
Recipe FAQs
They’re called monster cookies because they combine several ingredients—peanut butter, oats, candies, and sometimes chocolate chips or other mix-ins—making them a “monster” mash-up of flavors and textures.
A cookie scoop gives evenly sized cookies. Because oats limit spreading, you can lightly press the tops when they come out of the oven for round, even shapes.
Yes. The recipe uses a small amount of flour, which can be replaced with a 1:1 gluten-free baking flour or oat flour made from pulsed oats. Avoid replacing all flour with whole oats, as texture will change.
Try chopped peanut butter cups, chocolate chips, butterscotch chips, chopped pretzels, coconut flakes, or festive sprinkles. Use what you enjoy—these cookies are very adaptable.
Recipe Card: Oatmeal Monster Cookies
Oatmeal Monster Cookies
Ingredients
- 1 stick butter
- 1 cup brown sugar
- 1/2 cup white sugar
- 2/3 cup peanut butter
- 3 eggs
- 1/8 cup water
- 1 tbsp vanilla extract
- 1/4 cup all-purpose flour (or GF 1:1)
- 1/2 tsp cornstarch
- 3/4 tsp baking soda
- 1/2 tsp salt
- 3 1/4 cups old fashioned oats
- 1 cup M&Ms
Instructions
- Cream together softened butter, peanut butter, brown sugar, and white sugar.
- Beat in eggs, vanilla, and water until combined.
- Fold in flour, cornstarch, baking soda, and salt.
- Add the oats and M&Ms and mix until evenly combined.
- Refrigerate the dough for 20 minutes. Preheat oven to 350°F (175°C).
- Scoop dough onto a parchment-lined baking sheet.
- Bake 12–15 minutes or until edges are golden. Cool on a wire rack and enjoy.
Notes
Store in an airtight container in the refrigerator for chewier cookies, or at room temperature. Layer with parchment to prevent sticking. A cookie scoop helps keep portions even.
Nutrition (per cookie)
Calories: 224 | Carbs: 25 g | Protein: 5 g | Fat: 12 g
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