Thanks to a boxed cake mix these chocolate Cosmic Brownie Cookies are out of this world easy! The best fudgy chocolate frosted cookies with colorful rainbow chips. Everything you love about your favorite store-bought brownies you ate as a kid, in an irresistible copycat cookie!

We love the convenience of using a cake mix and still cranking out homemade flavor. Have you tried our dynamic-duo Peanut Butter Chocolate Chip Cake Mix Cookies, festive Peppermint Cake Mix Cookies w/Buttercream, or classic Cake Batter Puppy Chow Snack Mix.

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3 brownie cookies stacked with rainbow sprinkles

A cosmic brownie cookie is a chewy brownie topped with a thick layer of chocolate frosting and rainbow candy-coated chips. They were first made famous by the Little Debbie Company in 1999 and served as individually wrapped brownie bars.

Why Are They Called Copycat Recipes?

Any brownie labeled “cosmic” is inherently a copycat recipe since Little Debbie’s Cosmic® Brownies are the original fudgy brownie treat and registered trademark. While Little Debbie may have started the enduring craze for this beloved brownie dessert, decades later, the Crumbl Cookie franchise has taken up the banner with their Crumbl copycat Cosmic Brownie Cookies.

    Why Are They Called “Cosmic” Brownies?

    The “out-of-this-world” snack cake was created because of the popular cosmic bowling trend in the 1990s, featuring colorful glow-in-the-dark bowling pins, balls, lighted lanes, and fun music. The bright and “colorful candy-coated chocolate pieces” and the cosmic-inspired packaging get their signature look from this enduring family pastime.

    cosmic brownie cookies on a white plate with a pink background

    Why We Love Homemade Cosmic Brownie Cookies

    Prepare to embark on a delightful cosmic journey with our cake mix cosmic brownie cookies! Here are six irresistible reasons you’ll fall in love with these cookies:

    • Cosmic brownie cookies are a fantastic go-to for a charming and delicious homemade treat.
    • A mix of soft, fudgy centers and satisfyingly crispy cookie edges offer the best of both worlds in every bite.
    • Rich, homemade chocolate frosting with real cocoa takes this brookie recipe to a whole new level of decadence.
    • Vibrant rainbow chips add the signature pop of color to cosmic brownie cookies.
    • Customize homemade cosmic brownies with different flavors of cake mix, candy sprinkles, or nuts.
    • Visually appealing and oh, so delicious! Share at work, sell at bake sales, or invite someone over for coffee just because!
    ingredients for cosmic brownie cookies on a counter

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    Ingredients For Cosmic Brownie Cookies

    Packed with rich chocolate flavor and chewy texture, topped with colorful candy sprinkles for a fun and nostalgic touch, these super easy cake mix cookies are made with just 4 ingredients! (Ok, that is a slight of words since we’re making yummy homemade chocolate frosting, but those are simple pantry staples too.)

    For specific amounts, please refer to the printable recipe card at the bottom of the post.

    • Chocolate Cake Mix – one 15.25 oz box; my go-to is Duncan Hines 
    • Vegetable Oil – any neutral flavor oil you prefer
    • Large Eggs – bring to room temperature before using
    • Chocolate Chips – semi-sweet, dark chocolate, milk chocolate….whatever you please.

    Chocolate Fudge Frosting

    • Powdered Sugar – break up any lumps with a fork or a whisk
    • Cocoa Powder – Dutched cocoa (alkalized) will create a smoother chocolate flavor and deeper color than non-alkalized cocoa.
    • Milk – or use half and half or cream for a more decadent frosting
    • Vanilla & Almond Extract – creamy vanilla notes complement soft almond nuances that add depth to the chocolate frosting
    • Chocolate Rainbow Chips (as many as you want!)

    How To Make Cosmic Brownie Cookies

    Fudgy centers, crisp edges, and rich chocolate frosting crowned with cute cosmic candy toppings are your reward when you whip up a batch of these copycat cookies! Prep your baking sheet, heat up your oven, and get ready to be thrilled to the moon and back with cosmic brownie cookies!

    When you are making this recipe, you’ll want to use the full recipe at the bottom of the page.

    1. Mix the 4 cookie ingredients just until fully incorporated. Stir in chocolate chips, then chill the dough for 10-15 minutes.
    2. Use a cookie scoop to place even-sized dough balls on the cookie sheet.
    3. Bake cookies for 8-10 minutes (don’t overbake); cool on the pan for 5 minutes, then transfer to a wire cooling rack.

    Fudgy Frosted Layer:

    Of course, cookies must cool completely before frosting. The chocolate frosting will set quickly, so do them one at a time; frost and add sprinkles.

    1. Make the frosting by simply combining all of the frosting ingredients until smooth. 
    2. Frost the top and add the cosmic brownie sprinkles to each cookie. 
    3. Save some for others to enjoy!
    woman's hand holding a brownie cookie with rainbow chips

    Recipe Notes And Tips

    • You don’t want to preheat your oven until just before you are ready to pull the chilled cookie batter out of the fridge and make the brownie balls, especially if you have the rapid heating option with your oven.
    • Use a good quality chocolate cake mix. The better the cake mix, the better the brownie cookies will taste. 
    • Remember, overmixing the batter will make the cookies tough, so let’s not do that! 
    • Chilling the dough before baking is important because it helps the brookies retain their thick, fudgy texture and prevents them from spreading and becoming too thin.
    • Do not overbake cosmic brownies. Bake until the edges are set, and the centers are still slightly soft. The cookies will continue to cook as they cool on the baking sheet. 
    • Let the cookies cool completely before frosting or decorating so the chocolate topping doesn’t melt or slide off!
    • This fudgy chocolate frosting sets quickly, so frost one cosmic brownie cookie at a time, adding the sprinkles immediately so they will all adhere to the fudge icing
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    Another Important Note:

    Just a heads up – this Little Debbie copycat brownie recipe is so fabulous you might want to save yourself time by making a double batch! You’ve been warned!

    a plate of chocolate cookies with rainbow sprinkles


    Frosted brownie cookies will last up to 5 days in an airtight container in the fridge or for 3 months in the freezer.

    a plate of brownie cookies with rainbow sprinkles on white plates and a pink background

    Gifting Suggestions

    These festive frosted brownie cookies are always a hit with a crowd, whether young, older, or in between! No brownie lover can resist these chewy, fudgy brownies with chocolate cosmic rainbow chips.

    a plate of brownie cookies with rainbow sprinkles on fudgy frosting

    What Flavor Of Chocolate Cake Mix Do I Need For Brownie Cookies?

    The type of chocolate you prefer in your brownies is the flavor cake mix you should use for brownie cookies. Personally, I like a deep rich chocolate, so I usually reach for  Duncan Hines Dark Chocolate Fudge Cake Mix. If Devil’s Food or German Chocolate is your love language, then use it!

    a stack of three cosmic brownie cookies with rainbow chips

    Recipe Variations

    Last I checked, we don’t have a cosmic brownie cookie inspector (yet), so if you want to break tradition, you can definitely use other flavors of cake mixes in this recipe. (I won’t tell!)

    When making these cookies for a larger gathering, a second or third batch with different cake flavors is visually appealing and gives “non-chocolate fans” an option. (I’ve been told they exist, but not a creature I’ve ever beheld!) Butter Golden or Red Velvet would be wonderful with the chocolate frosting!

    Any nut milk will work if you want to sub the cow milk in the chocolate icing. You can even use water, but I’d try jazzing it up with cold coffee instead to pull in a few toasty cocoa notes. 

    If you like cosmic brownies with nuts, try peanuts, walnuts, or treat your palate to a macadamia brownie, yum!

    chocolate cookies on white plates

    Like This Recipe?

    I’d love to hear what you think! Leave a review below and let me know how you liked the recipe!

    a stack of three cosmic brownie cookies with rainbow chips

    Copycat Cosmic Brownie Cookies

    Yield: 15 cookies
    Prep Time: 10 minutes
    Cook Time: 8 minutes
    Chill Time: 15 minutes
    Total Time: 33 minutes

    Thanks to a boxed cake mix these chocolate Cosmic Brownie Cookies are out of this world easy! The best fudgy chocolate frosted cookies with colorful rainbow chips. Everything you love about your favorite store-bought brownies you ate as a kid, in an irresistible copycat cookie recipe!


    • 1 (15.25 ounce) box chocolate cake mix
    • ½ cup vegetable oil
    • 2 large eggs, room temp
    • 1 cup semi-sweet chocolate chips
    • 1 ½ cups powdered sugar
    • ⅓ cup cocoa powder
    • ¼ cup milk
    • 1 teaspoon vanilla extract
    • 1 teaspoon almond extract
    • Chocolate rainbow chips (as many as you want!)


    1. Line a baking sheet with parchment paper or a silicone baking sheet and set aside. 
    2. In a large mixing bowl, using an electric mixer on low combine eggs, cake mix, and oil just until powdered cake mix is fully incorporated. Stir in chocolate chips and refrigerate the dough for 10-15 minutes.
    3. Preheat oven to 350° F. while scooping out cookies. Using a 2-tablespoon cookie scoop, portion out even-sized dough balls, placing them 2 inches apart on the prepared pan. 
    4. Bake for 8-10 minutes. Don’t overbake. It’s ok if the center is slightly wet, they will continue to bake as they cool on the pan. Cool cookies for 4-5 minutes on the pan then transfer cookies to a cooling rack.
    5. Allow the cookies to fully cool before frosting. 
    6. While the cookies are cooling, make the frosting. In a large mixing bowl, combine powdered sugar, cocoa powder, milk, vanilla, and almond extract until smooth. 
    7. Using an offset spatula (or butter knife), smooth frosting on the top of each cooled cookie and sprinkle with the rainbow chips. Enjoy!


    This frosting dries fast, so frost one cookie, add sprinkles, then move onto the next cookie or your sprinkles won’t stick. 

    Make sure to not over-bake the cookies. They will seem soft right out of the oven, but will firm up as they cool.

    Frosted brownie cookies will last up to 5 days in an airtight container in the fridge or for 3 months in the freezer.

    Nutrition Information:
    Yield: 15 Serving Size: 1
    Amount Per Serving: Calories: 191Total Fat: 12gSaturated Fat: 3gTrans Fat: 0gUnsaturated Fat: 8gCholesterol: 25mgSodium: 27mgCarbohydrates: 21gFiber: 1gSugar: 18gProtein: 2g

    Nutrition information is estimated based on the ingredients and cooking instructions as described in each recipe and is intended to be used for informational purposes only. Please note that nutrition details may vary based on methods of preparation, origin, and freshness of ingredients used and are just estimates. We encourage, especially if these numbers are important to you, to calculate these on your own for most accurate results.

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    cookies with rainbow sprinkles on chocolate frosting