Brown Butter Monster Mash Cookies

Soft and chewy peanut butter cookies with nutty oats, M&Ms, semi-sweet chocolate, and salty pretzels to finish—they’re such a simple treat and are perfect to make for the Halloween season!

There’s nothing I love more than a good cookie recipe, and with Halloween right around the corner, these brown butter monster mash cookies are the perfect recipe to make! I created these cookies to be a mix of the popular “kitchen sink” cookies and my brown butter monster cookie bars, so they have the perfect balance of salty pretzels, chewy oats, and nutty peanut butter!

Ingredients in Monster Mash Cookies

Most of the ingredients for these cookies are pantry staples, so you most likely already have them in your house! Here’s a breakdown of what you’ll need:

• Unsalted butter. Butter is an important ingredient in this recipe—they’re called brown butter monster mash cookies for a reason! If you don’t feel like browning your butter, you can substitute it with 8 tablespoons of cooled, melted butter.
• Peanut butter. A processed peanut butter like JIF or Skippy is best for this recipe, since natural brands have too much oil.
• Light brown sugar.
• Granulated sugar.
• Eggs.
• Vanilla.
• All-purpose flour. Be sure not to over-measure your flour, otherwise you’ll have cookies that are too dry and won’t spread. Instead, spoon the flour into your measuring cup and level it off to get an accurate amount.
• Old-fashioned rolled oats. Don’t use instant or steel-cut oats! Old-fashioned oats have the perfect amount of chewiness and texture for these cookies.
• Baking soda.
• Kosher salt.
• M&Ms. I like to use Halloween-colored M&Ms to make them extra festive!
• Mini pretzels. I use Snyder’s mini pretzels for a perfect balance of sweet and salty.
• Semi-sweet chocolate chips. Using chocolate chips in addition to M&Ms will give the cookies melty pockets of chocolate throughout.

What is Brown Butter?

In a nutshell, brown butter is just toasted butter. When you cook butter past its melting point, the water evaporates and the milk solids toast (these are the dark brown spots you see after it’s done cooking) to give it a nutty smell and flavor. Here are a few tips when it comes to browning butter:

1. Use a light-colored pan. Butter can easily go from browned to burned—by using a light-colored pan, you’ll be able to tell when your butter is done cooking.
2. Cook on medium-low heat. A steady and low heat will let your butter cook evenly and will prevent it from burning.
3. Have an extra bowl on hand. Once the butter is done cooking, you’ll want to pour it into a bowl immediately—if you leave it, the residual heat will continue to cook it, and the butter will burn!

Make Ahead Instructions

You can make the cookie dough up to two days in advance, and you can even freeze the dough to bake later!

• To refrigerate. Once the dough is made, scoop out the cookies and refrigerate anywhere from 30 minutes to 48 hours—this resting time allows the cookies to fully absorb the flour and intensify in flavor.
• To freeze. If you want freshly baked cookies whenever you want, freeze it! Scoop all of the dough onto a baking sheet and freeze for 1 hour to harden, then transfer the cookie dough to a plastic bag. When ready to bake, there’s no need to thaw! Just pop however many cookies you want onto a baking sheet and cook them from frozen—but keep in mind that they might need a minute or two longer to cook.

Other Halloween Recipes

If you love spooky season as much as I do, you’ll want to take a look at these fall-inspired recipes!

• Brown Butter Monster Cookie Bars
• Homemade Caramel Apples.
• Perfect Pumpkin Bread.

Happy cookie baking! Leave any questions, comments, or ratings below and let me know if you like the recipe!

Monster Mash Cookies

Soft and chewy peanut butter cookies with nutty oats, M&Ms, semi-sweet chocolate, and salty pretzels to finish—they're such a simple treat and are perfect to make for the Halloween season!

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Course: Dessert

Keyword: cookies

Servings: 18 cookies

Author: Mae Martin

Ingredients

• 10 tablespoons unsalted butter*
• ½ cup smooth peanut butter, such as JIF**
• ½ cup light brown sugar
• ¼ cup granulated sugar
• 1 egg
• 2 teaspoons vanilla extract
• 1 cup all-purpose flour
• ¾ cup old-fashioned oats
• ½ teaspoon baking soda
• ½ teaspoon kosher salt
• ½ cup M&Ms
• ¼ cup mini pretzels
• ¼ cup semi-sweet chocolate chips

Instructions

• Cut the butter into cubes and place in a large saucepan. Set the pan over medium heat and stir until melted. Continue to stir the butter every ten seconds or so, until it bubbles and begins to foam. Once you see brown bits floating in the butter and a nutty aroma is released, immediately remove the pan from the heat.
• Pour the butter into a bowl to stop the cooking process, making sure to get all the browned bits from the bottom of the pan. Allow the butter to cool to room temperature, or set it in the fridge for around 30 minutes to speed up the process.
• In the meantime, mix together the flour, oats, baking soda, and cinnamon in a medium bowl until well combined. Set aside.
• When the butter is cooled, pour it into a large bowl with the peanut butter and whisk until smooth. Add the brown sugar and granulated sugar and mix for 1-2 minutes. Beat in the egg and vanilla.
• Once the wet ingredients are well mixed, add in the dry ingredients, M&Ms, pretzels, and chocolate. Stir the mixture together until a dough forms (be careful not to overmix). If the dough is too sticky, add 1-2 tablespoons more flour—you should be able to pinch a bit of dough without getting a lot of sticky residue on your fingers.
• Scoop the dough onto a baking sheet lined with wax or parchment paper. Cover the tray with plastic wrap and refrigerate for at least 30 minutes but up to two days. At this point, the cookie dough can be frozen.¹
• Preheat the oven to 375℉ and line a baking sheet with parchment paper.
• When ready to bake, evenly space the cookie dough balls onto the baking sheet with a 2'' gap between each cookie. If desired, press the top of the dough with more M&Ms and pretzels.
• Bake for 10-12 minutes, rotating the tray halfway through. Remove the cookies from the oven once the edges are golden brown and set, but do not overbake (they will set more as they cool). Once out of the oven, sprinkle the cookies with flaky salt and allow to cool before serving.

Notes

*If you don’t want to brown the butter, simply substitute with 8 tablespoons of cooled, melted butter.

 

**Be sure to use a brand like JIF or Skippy. Natural peanut butter made from just peanuts and salt will not work in this recipe.

1. If you plan on refrigerating the cookie dough, I recommend scooping it beforehand. Otherwise, the dough will harden and become too difficult to scoop. To freeze, portion the cookie dough onto a baking sheet and place it in the freezer for 1 hour. Once firm, store the dough balls in a plastic bag in the freezer for 3-6 months. To cook, follow the baking instructions as written (no need to thaw the dough), though the cookies may need a couple of more minutes to cook.