Chewy peanut butter oatmeal cookies studded with milk chocolate chips, mini M&M’s, and corn flakes makes about 24 large cookies. Perfect for your leftover Halloween candy or for your Halloween party!

Monster cookies are typically filled with chocolate candy, chocolate chips, something salty and crunchy, and chewy oatmeal. To me, they are the ideal Halloween-time cookie. You can adjust these cookies to include the chocolate candies you prefer or change up the crunch salty addition for a totally new cookie.

The original recipe comes from Two Peas & Their Pod’s cookbook, and I skipped over making it for a long time since the picture they in the cookbook is just of the cookie dough, and I am much more likely to make something if I know what the finished product looks like. When I had my home bakery, I decided to try it out to make a Fall/Halloween cookie. I tweaked the recipe a little to suite my own preferences, and have kept it pretty much the same since, though I have had fun adjusting the mix-ins.

Ingredients & Substitutions:

• All-purpose flour: Plain all-purpose flour works best for this recipe, I added a little more compared to the original to make a thicker cookie. You could try bread flour for an even sturdier cookie or gluten free flour.

• Rolled oats: Makes this recipe chewy and delicious. I would not skip or try to sub for flour, or you will get a completely different cookie.

• Baking soda: The leavening agent, do not skip.

• Sea salt: To balance the sweetness and add depth to the flavor of the cookie

• Creamy salted peanut butter: You could sub for crunchy peanut butter or another nut butter if you prefer; do not skip this ingredient

• Unsalted Butter: To bring everything together and create a balanced cookie; could use vegan butter as a substitute

• Brown sugar: Can sub with white sugar plus 2 tsp molasses if you don’t have any, adds depth and flavor to the cookie.

• White sugar: Could sub for brown sugar if you don’t have any for a slightly different cookie.

• Vanilla extract: To add flavor, can skip in a pinch if you don’t have any or sub for vanilla bean paste 1:1.

• Large eggs: To emulsify, add texture, and leavening to the cookie

• Corn flakes: The original version of this recipe calls for pretzels, but I recently substituted for them with cornflakes, and I actually like them more! You can also sub for both of these with plain salted potato chips

• Milk Chocolate chips: The original recipe calls for semi-sweet, but milk chocolate is my preference here. You can also substitute for mini peanut butter cups.

• Mini M&M’s: You can use regular sized, peanut, or peanut butter versions if you prefer, but I like the smaller ones because they are more crunchy

• Flakey sea salt: Optional, to sprinkle on the top of the cookie before baking

Why You’ll Love this Recipe

• It can be adapted to suite what you have in your pantry (see above for substitutions) or to include more of your favorite type of chocolate candy

• You can freeze the dough to have on hand. Just bake 25° cooler at 350°F for about 12-14 minutes

• The cookies are fun and colorful from the addition of M&Ms

• You can make huge (or “monster”) sized versions of these cookies, and use a 1/2 cup measuring cup to measure. Reduce heat to 350° if you do

Frequently Asked Questions

• Can this recipe be made gluten free? Your best bet is using King Arthur Flour Gluten Free Bread Flour, but that is not safe for people with wheat allergies. If you us a gluten-free flour blend, then add 3/4 tsp of xantham gum to the dry ingredient mix, and be sure your oats and corn flakes are certified gluten-free.

• Can this recipe be made vegan? I haven’t personally tried this, but theoretically if you did standard vegan butter and egg substitutions along with vegan mix ins, it should work! If you try it, please let me know in the comments.

• Can this recipe be made peanut free? It would definitely have a different overall feel, but you could try to substitute a different nut butter that didn’t have peanuts.

• Can this recipe be made in advance? This dough freezes beautifully for up to two months. Bake straight from frozen at 350°F instead of 375°F.