High Altitude Flourless Monster Cookies (GF, Dairy Free)

The easiest recipe for soft and chewy, high altitude flourless monster cookies, made with oats and peanut butter, and loaded with M&Ms and chocolate chips. These colorful cookies come together fast, with no mixer needed and no chill time.

You might also love these gluten free high altitude recipes for flourless peanut butter chocolate chip cookies, flourless almond cake, and flourless chocolate cake with bourbon vanilla whipped cream.

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What are Monster Cookies?

Monster cookies are easy to make drop cookies that always contain oats, peanut butter, chocolate chips and M&Ms. Some recipes may even include other add-ins, like butterscotch chips, salted peanuts, pretzels, toffee bits, potato chips or shredded coconut. The cookies may or may not contain butter, and can easily be made flourless, too. They’re big, thick, soft, chewy, hearty cookies that are easy to love.

So why are they called monster cookies? They are thought to have earned the name from their combination of so many different ingredients – like the monster Frankenstein! And since these peanut butter oatmeal cookies are loaded with so many add-ins, they’re sometimes called “kitchen sink cookies”, too. The candy eyeballs are optional, but I had some on hand, and I knew my kids would love them.

Why You’ll Love This Recipe

Easy to Make. These cookies are ridiculously easy. The dough will come together in just 5 minutes, with a bowl and spoon.

No Chill Time. You don’t have to chill the dough before baking, just mix, scoop and bake!

Customize for the Holidays. With different colors of M&Ms available for each season and holiday, you can easily customize these cookies for Easter, Valentine’s Day, 4th of July, Halloween or Christmas.

Gluten Free. I’ve had great feedback on my flourless peanut butter chocolate chip cookies, which are gluten free and dairy free. It’s hard to find good high altitude tested, gluten free recipes that don’t use expensive gluten free flour. One important thing to note, though, is regarding the oats. While oats are naturally gluten free, they are often contaminated with gluten from other grains, such as barley, wheat and rye. This contamination can happen at the farm, in storage, during transportation or at a packaging facility. So cookies containing oats may still contain gluten, unless the oats you’re using are certified gluten free. Please check the package before making these for someone with celiac disease.

Dairy Free. With no butter in today’s recipe, these flourless monster cookies are dairy free. They are not vegan, though, since they contain eggs. However, M&Ms do contain milk-based ingredients.

High Altitude Tested. I develop all the recipes on my site for Denver’s altitude of 5,280 feet. If you’re at a lower or higher elevation, please see my FAQs for guidance on adjusting recipes for your altitude.

See the recipe card at the end of the post for the full ingredients list and instructions.

Ingredients

• Peanut Butter. You can use creamy or crunchy peanut butter, whichever you prefer. If you use an all natural, drippy peanut butter, use 2 tablespoons less than the recipe calls for.
• Sugar. A combination of granulated sugar and light brown sugar adds sweetness and helps the edges of the cookies to brown and caramelize.
• Eggs. Binds the dough together, and adds moisture, since oats are very absorbent.
• Vanilla Extract. Flavor.
• Baking Soda. Leavening agent.
• Salt. Balances the sweetness.
• Oats. Use old fashioned rolled oats, not quick oats or steel cut oats. Make sure the package says “gluten free” if you want to make sure your cookies are gluten free.
• Chocolate Chips, M&Ms, and Candy Eyeballs.

Instructions

• Preheat the oven to 350 F, and position a rack in the center of the oven. Line a baking sheet with parchment paper.
• In a bowl, stir together the peanut butter, granulated sugar, brown sugar, eggs, vanilla, baking soda and salt, until well combined.
• Add the oats, 1/2 cup of chocolate chips and 1/2 cup of M&Ms. Stir together into a soft, sticky dough.

• Use a large cookie scoop (3 tablespoon capacity) or cupcake scoop with a release lever to scoop the dough and drop it onto the baking sheet, leaving 3 inches between each cookie (I recommend baking just 6-8 cookies at a time). Do not flatten the dough.
• Bake the cookies for exactly 9 minutes. Take the pan out of the oven, and immediately use a round cookie cutter (one that’s larger than the circumference of the baked cookies) and “scoot” it around the hot cookies. This pulls in the uneven edges and makes your cookies perfectly round and uniform.
• Let the cookies cool on the baking sheet for 5 minutes. While they cool, decorate the tops of the hot cookies with the remaining 1/4 cup each of chocolate chips and M&Ms, and the candy eyeballs.

• Gently transfer the cookies to a cooling rack and cool completely.

TIP: Although the center of the cookies will seem under-baked after just 9 minutes, the oats will absorb moisture and the cookies will set up perfectly as they cool. If you over-bake these cookies, they’ll end up dry and crunchy as they cool, instead of soft and chewy.

Tips for Perfectly Pretty Cookies

Always scoot your cookies.

Cookie scooting is a common practice with food photographers and bloggers. It’s the simplest way to elevate the appearance of your cookies. Since most cookies tend to spread a little unevenly as they bake, cookie scooting pulls in those uneven edges, making your cookies perfectly round and uniform in size.

All you need is a round cookie cutter or biscuit cutter that’s larger in circumference than your baked cookies. As soon as you take the pan of cookies out of the oven, take the cookie cutter and scoot it around the hot edges, pulling them in a little. You have to do this quickly, before the cookie sets. You’ll love how much prettier your cookies will look after cookie scooting.

Decorate the tops of the cookies.

The chocolate chips and M&Ms in the cookie dough rarely position themselves perfectly on top of the cookies as they bake and spread. So I pretty much always decorate the tops of my baked cookies with more of what’s inside. Do this while the cookies are hot, so the toppings melt a little and stick to the cookies. This simple step really takes the cookies from looking rather blah to so beautiful.

Be sure to read all of my BAKING FAQs where I discuss ingredients, substitutions and common baking questions, so that you can be successful in your own baking!

Frequently Asked Questions

Are oats gluten free?

While oats themselves are gluten free, they may be contaminated with gluten from other grains they’ve come into contact with. Be sure you’re using oats that are labeled as “gluten free” if you’re making these cookies for someone with celiac disease.

How long do these cookies stay soft?

Monster cookies will stay soft and chewy, stored in an airtight container at room temperature, for up to 3 days.

Can these cookies be frozen?

Yes, they can. After the cookies cool completely, store the cookies in an airtight container or freezer bag for up to 3-6 months.

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