Name: Costco Marshmallow Crispy Cookies
Prep time: 15 min
Cook time: 12 min
Total time: 27 min
Cuisine: American
Ingredients: 1 cup unsalted butter, softened; 1 cup brown sugar; 1/2 cup white sugar; 1 large egg; 2 teaspoons vanilla extract; 1 1/2 cups all-purpose flour; 1/2 teaspoon baking soda; 1/2 teaspoon salt; 2 cups old-fashioned oats; 1 1/2 cups mini marshmallows

If you’ve ever bitten into one of Costco’s iconic Marshmallow Crispy Cookies, you already know they’re not your average treat. These golden, chewy delights combine the buttery crunch of oatmeal cookie dough with a molten marshmallow center that oozes out in the most magical way. Every bite is a perfect mix of textures: crisp edges, a soft chewy interior, and that irresistible creamy middle.

Inspired by this cult-favorite, we’ve recreated them right in your kitchen. They’re not just a copycat version—they might be even better. Perfect for lunchbox treats, cozy movie nights, or potluck table stars, these cookies are a sure-fire hit for both kids and grown-ups who crave nostalgic comfort with a gooey twist.

Why You’ll Love This Costco Marshmallow Crispy Cookies

Soft and chewy with a gooey surprise: The melty marshmallow center elevates a simple oatmeal cookie into something extraordinary.
Simple pantry ingredients: No fancy stuff here—just real, comforting flavors.
Fun to make and eat: Watching that marshmallow pull apart is half the joy.
Perfect for sharing: They’re crowd-pleasers, great for bake sales, parties, or freezer-stashing.

Preparation Phase & Tools to Use

To master these gooey-centered cookies, the right preparation makes all the difference. Here’s what you’ll need:

Mixing Bowls (Large & Medium): You’ll separate your dry and wet ingredients, so two bowls are key for clean combining.
Electric Mixer or Stand Mixer: Creaming butter and sugars until fluffy is crucial. A hand or stand mixer will get you there fast.
Cookie Scoop: Ensures uniform dough balls, so every cookie bakes evenly and encases the marshmallow perfectly.
Parchment Paper or Silicone Baking Mat: Prevents sticking and promotes an even bake. Essential for marshmallow melting moments.
Baking Sheet: A flat, sturdy surface is non-negotiable. A light-colored pan works best to avoid overbrowning.

Ingredients for the Costco Marshmallow Crispy Cookies

Unsalted Butter: Brings that classic buttery cookie flavor and helps with chewiness.
Brown Sugar: Adds depth and moisture for that soft texture.
White Sugar: Balances the sweetness and helps crisp the edges.
Egg: Binds everything together for structure.
Vanilla Extract: Enhances the warmth and sweetness of the cookie.
All-Purpose Flour: The backbone of the cookie structure.
Baking Soda: Helps the cookies rise just the right amount.
Salt: Enhances all the flavors.
Old-Fashioned Oats: Gives that hearty, chewy base with a hint of nutty flavor.
Mini Marshmallows: The gooey, molten heart that makes these cookies unforgettable.

How To Make the Costco Marshmallow Crispy Cookies

Step 1: Cream the Butter and Sugars

In a large bowl, beat together the softened butter, brown sugar, and white sugar until fluffy. This helps create a soft, chewy cookie.

Step 2: Add Wet Ingredients

Mix in the egg and vanilla extract until everything is fully incorporated.

Step 3: Combine the Dry Ingredients

In a separate bowl, whisk together the flour, baking soda, and salt. Then gradually add this mixture into your wet mixture.

Step 4: Stir in the Oats

Fold in the old-fashioned oats until evenly distributed through the dough. The texture should be thick and scoopable.

Step 5: Shape and Stuff

Scoop about 1.5 tablespoons of dough, flatten it slightly, place 2-3 mini marshmallows in the center, then seal it closed and shape into a ball.

Step 6: Bake to Perfection

Place on a lined baking sheet and bake at 350°F (175°C) for 10-12 minutes or until edges are golden and centers look slightly underdone. Let them cool on the tray—the marshmallow needs to settle.

Serving and Storing These Gooey Treats

Serve these cookies slightly warm for the ultimate melt-in-your-mouth experience. Pair with a glass of cold milk or a scoop of vanilla ice cream for pure bliss.

To store, let cookies cool completely and place in an airtight container. They stay fresh at room temp for up to 4 days. For longer storage, freeze the baked cookies for up to 2 months—just warm them slightly before serving to reawaken that marshmallow magic.

Frequently Asked Questions

Can I use regular marshmallows instead of mini?

Yes, but cut them into smaller pieces. Mini marshmallows distribute better and melt evenly.

Absolutely! Freeze the dough balls (unstuffed or stuffed), then bake straight from the freezer by adding 1-2 extra minutes to the bake time.

How do I stop the marshmallows from leaking out?

Make sure you completely seal the dough around them. Also, chill the dough before baking to help prevent early spreading.

Can I make them gluten-free?

Use a 1:1 gluten-free flour substitute and certified gluten-free oats.

Do I need to chill the dough?

It’s optional, but chilling for 30 minutes helps with a thicker, chewier cookie and controls spreading.

Can I add chocolate chips or nuts?

Definitely! A few mini chocolate chips or chopped pecans make delicious additions.

If you love these Costco marshmallow crispy cookies, check out these other sweet favorites:

Simple Apricot Cream Cheese Thumbprint Cookies for fruity, creamy goodness.
Reese’s Peanut Butter Banana Bread if you’re into that sweet, salty duo.
Pecan Pie Lasagna when you want layered decadence.
Brownie Refrigerator Cake for no-bake chocolate dreams.
Cinnamon Sugar French Toast Muffins for cozy brunch or dessert.

Save This Pin For Later

📌 Save this recipe to your Pinterest dessert board so you can come back to it any time.

And let me know in the comments how yours turned out. Did you add chocolate chips? Did you try a caramel center instead? I love hearing your creative twists. Questions are welcome too—let’s help each other bake smarter.

Find more daily sweet creations on my Pinterest: Kitchen By Kate on Pinterest