Copycat Costco Marshmallow Krispies Cookies Recipe

If you’re a fan of Rice Krispies Treats, you might be familiar with Costco’s delightful marshmallow-flavored sugar cookies. These cookies, which debuted earlier this year, offer the delightful combination of a sugar cookie with the soft, chewy texture of marshmallow treats. I was eager to try them, and luckily, a generous friend, a frequent Costco shopper, brought a pack over for me to sample. Below is a picture of the actual Costco marshmallow Rice Krispies cookies.

Texture and Flavor of Costco’s Marshmallow Cookies

These Costco cookies have that signature extra-firm chewiness often found in grocery store bakery items. Additionally, they offer a subtle burst of buttery flavor that complements the Rice Krispies, evoking the taste of browned butter Rice Krispies Treats. As you can see in the image above, the marshmallows retain a creamy consistency and don’t dry out.

Recreating the Costco Marshmallow Krispies Cookies at Home

Inspired by the Costco cookies, I wanted to recreate a similar version at home. Given my extensive collection of cookie recipes, I thought it would be relatively simple. I decided to use a recipe called “50 Good Cookies” as a base and make the necessary adjustments. And there were indeed quite a few adjustments required!

Achieving the Sweet, Chewy, and Buttery Cookie Perfection

The Costco cookies are undeniably sweet. While the “50 Good Cookies” recipe is also sweet, I needed to enhance the chewiness. To do this, I used a combination of white sugar, brown sugar, corn syrup, and King Arthur all-purpose flour. For added tenderness and a pleasant mouthfeel, I incorporated a small amount of non-dairy coffee creamer – just a simple, unflavored Coffee Mate powder. The key to replicating the buttery flavor of the Costco cookies was using butter flavoring. My taste testers consistently commented on the delicious buttery taste of the cookies, which real butter flavor would not fully create. It tastes more like they may have butter extract.

The Marshmallow Challenge

The marshmallows proved to be a challenge. Initially, they tended to melt into the cookies and then dry out, unlike the creamy, opaque marshmallows found in the Costco version. To address this, I flattened regular marshmallows and placed them in the freezer. Freezing the marshmallows helped them retain their shape better during baking. I also experimented with dehydrating marshmallows using my Breville Smart Oven for five hours. The dehydrated marshmallows worked wonderfully! They still melted slightly, but didn’t spread as much.

The Importance of Half an Egg

Here’s the catch: I’ve kept this recipe to myself for months because it seems to only work correctly with exactly two tablespoons of beaten egg, which some people find an odd measurement. I tried versions with a full egg, but the texture wasn’t the same—the cookies became cakier and softer. The defining characteristic of the original cookies is their chewiness, so the egg quantity must be precise. Please use only half an egg if you attempt this recipe. However, if you find a way to improve the recipe with a whole egg (or even no egg), please let me know!

Subtle Additions: Quick Oats and White Chips

Another distinction from Costco’s version is the addition of oats, which provide a slight structure and enhanced chewiness. These aren’t intended to be oatmeal cookies, so I use quick oats as they are less pronounced. I also added a touch of white chips, just enough to deliver a burst of sweetness without overpowering the other flavors.

Helpful Tips for Perfecting Your Cookies

• Measure Flour Accurately: Always measure the flour by weight. If you cannot find King Arthur all-purpose flour, try using bread flour as a substitute.
• Ensure Freshness of Vegetable Oil: Use fresh vegetable oil. I’ve found that grapeseed and sunflower oil tend to be more neutral in flavor, while canola oil can sometimes develop an unpleasant taste if it has been stored for too long.
• Resist Adding More Rice Krispies: It’s tempting to add more Rice Krispies, but resist! I experimented with a full cup, but too many Rice Krispies resulted in a mealy texture. While more may work well in other recipes, these cookies only need half a cup.
• Prevent Spreading: To prevent the cookies from spreading too much, line your baking sheet with parchment paper. If you have an insulated baking sheet like an AirBake, use that. Alternatively, stack a large baking sheet on top of a smaller rimmed baking sheet. This will help reduce spreading and prevent the bottoms from browning too quickly.
• Chill the Dough (Optional): Chilling the dough is not essential, but it will make the cookies a little thicker and give them a more rounded shape.

• Kirkland Mixed Nut Butter Chocolate Chunk Cookies
• Small Batch Chocolate Peanut Butter & Krispies Topped Brownies
• Marshmallow and Rice Krispies Topped Brownies
• Peanut Butterscotch and Toasted Pecan Krispies
• Milk Chocolate Peanut Butter Rice Krispies Treats

Recipe