Fudgy, brownie-like cookies crowned with glossy chocolate ganache and a confetti of rainbow chips are a revamp of one of my childhood favorites! Ready in under 30 minutes, they’re a party-worthy treat for birthdays, bake sales, and cookie swaps.
Crumbl, the Utah-born cookie shop, is famous for its ever-changing weekly menu, which is all fine and dandy until your favorite cookie doesn’t show up for months. So I decided to make my own version of the Little Debbie’s lunchbox classic inspired Cosmic Brownie into a cookie with fudgy chocolate, glossy frosting, and rainbow chips on top. Dare I say it’s vastly superior to the pink box version? It also works great with measure-for-measure gluten-free flour.
These cookies are basically brownies in cookie form. They’re deep, dark, and fudgy, thanks to a full cup of Hershey’s Special Dark cocoa. The centers stay soft, the edges hold their shape, and a spoonful of glossy ganache that firms up as it sets makes them look like they came straight from the bakery case.
The best part is how easy they are. Prep takes 15 minutes, the bake takes 12, and the ganache is just two ingredients stirred together. My husband once swore (years ago now) that boxed brownies beat homemade, but these are exactly the kind of treat that settles that argument for good and ever.
For more Crumbl copycat cookies, check out my Buckeye Brownie Cookies, Chocolate Oreo Cookies, Churro Cookies, Cinnamon Swirl Cookies, and Peanut Butter Muddy Buddies Cookies.
Why you’ll love this recipe!
- A full cup of Hershey’s Special Dark cocoa gives them deep chocolate flavor, a fudgy center, and chewy edges.
- Two-ingredient ganache and rainbow chips make them look bakery-worthy in minutes.
- Prep takes just 15 minutes, there’s no need to chill the dough, and unfrosted cookies freeze for up to 3 months.
What You’ll Need
Scroll down to the recipe card below this post for ingredient quantities and full instructions.
- Hershey’s Special Dark Cocoa Powder: Gives the cookies their deep, fudgy, brownie-like flavor and dark color. Any unsweetened cocoa powder works in a pinch at the same amount, but the cookies come out a little lighter and less intense.
- Semisweet Chocolate Chips: Melts into the glossy ganache that crowns every cookie. Milk or dark chocolate chips work at the same amount, and so does a chopped chocolate bar.
- Heavy Cream: Turns the chocolate chips into a silky, spoonable ganache. Heavy whipping cream is the same thing, so use whichever one you find.
- Salted Butter: Adds rich flavor and keeps the centers soft. Let it come to room temperature so it creams smoothly. Unsalted butter works too, just add an extra ½ teaspoon of salt.
- Light Brown Sugar: Adds moisture and a hint of caramel for soft, chewy cookies. You can swap in dark brown sugar at the same amount for a slightly deeper flavor.
- Granulated Sugar: Sweetens the dough and gives the edges a little crispness.
- Large Eggs: Binds the dough and adds richness. Room temperature eggs mix in more smoothly.
- Pure Vanilla Extract: Rounds out the chocolate with a warm, mellow background note.
- Light Corn Syrup: Adds chew and helps the cookies stay soft. You can swap in honey at the same amount.
- All-Purpose Flour: Gives the dough structure so the cookies hold their shape. Spoon it into the measuring cup and level it off, since packing it in makes dry, cakey cookies.
- Cornstarch: Keeps the centers soft and tender.
- Baking Soda: Gives the cookies a little lift and helps them spread into thick pucks. Baking powder is not a substitute.
- Salt: Sharpens the chocolate flavor and balances the sweetness.
- Rainbow Chip Sprinkles: Adds the colorful candy confetti that makes these cosmic. Mini M&M’s work in a pinch.
How to Make Copycat Crumbl Cosmic Brownie Cookies
- Preheat oven. Heat the oven to 350°F (177°C) and line your baking sheets with parchment paper.
- Cream butter and sugars. In a large bowl, beat the butter, brown sugar, and granulated sugar for 2-3 minutes, until creamy and light.
- Add eggs, vanilla, and corn syrup. Mix on medium speed until combined, stopping to scrape the bottom and sides of the bowl.
- Mix in dry ingredients. Add the flour, cocoa powder, cornstarch, baking soda, and salt. Mix on medium-low speed just until combined and no streaks of flour remain.
- Scoop and shape. Use a large ¼ cup cookie scoop (4 Tablespoons) to portion the dough into big mounds, then roll them into balls. Press each one into a puck about ½” thick and space them a few inches apart on the baking sheets, with no more than 6 per sheet.
- Bake and cool. Bake for 11-12 minutes, until the edges are set. Don’t overbake, since the centers can look slightly doughy or wet and will finish setting as they cool on the hot pan. Let the cookies cool completely.
- Make ganache. Heat the cream until it bubbles, then pour it over the chocolate chips. Let it sit for 5 minutes, then stir until smooth.
- Top and chill. Spoon 1 Tablespoon of ganache onto each cookie and sprinkle with rainbow chips. Chill in the fridge until completely set before serving.
Recipe FAQ’s
Ganache firms up as it chills, so the topped cookies need time in the fridge. Make sure the cookies are completely cool first and the hot cream sits on the chocolate chips for the full 5 minutes before you stir.
They hit the same notes: fudgy chocolate, a ganache topping, and rainbow chips. The difference is a soft cookie bite instead of a cake-like brownie.
Yes, use a 2 Tablespoon scoop and bake for 8-10 minutes.
Store frosted cookies in a single layer in an airtight container at room temperature for up to 3 days. If you need to stack them, place parchment paper between the layers to keep the ganache neat.
Yes, freeze unfrosted cookies in a single layer on a baking sheet, then transfer them to a ziplock bag once solid, and they’ll keep for up to 3 months. Thaw them at room temperature, add the ganache, and chill until set.
Tips for Success
- Mix the flour in just until no streaks remain but no more. Overmixing develops gluten and makes the cookies tougher instead of soft and fudgy.
- Portion the dough with a large ¼ cup cookie scoop so every cookie is the same size and finishes baking at the same time.
- Bake no more than 6 cookies per sheet and space them a few inches apart, so each one has room to spread and bakes evenly.
- Take the cookies out at 11-12 minutes, when the edges are set but the centers still look slightly doughy, because they keep cooking on the hot pan and an overbaked cookie turns dry instead of brownie-soft.
- Let the cookies cool completely before adding the ganache, since warm cookies melt it and it slides right off.
- Let the hot cream sit on the chocolate chips for the full 5 minutes before stirring, so the chips melt evenly and the ganache comes out smooth and glossy.
Substitutions and Variations
- Stir ½ teaspoon of peppermint extract into the ganache and top the cookies with crushed candy canes instead of rainbow chips for a chocolate-mint version.
- Swap the rainbow chips for crushed Oreos or chopped Reese’s Peanut Butter Cups to give the cookies a cookies and cream or peanut butter twist.
- Fold ½ cup of chopped walnuts or pecans into the dough for a nutty crunch, and bake as directed.
- Fold ½ cup of mini chocolate chips into the dough for a double chocolate bite.
- Drizzle caramel sauce over the ganache and add a pinch of sea salt for a salted caramel version.
More Big Bakery-Style Cookie Recipes You’ll Love
- Levain Chocolate Peanut Butter Chip Cookies
- Levain Chocolate Chip Cookies
- Jacques Torres Chocolate Chip Cookies
- Butterfinger Cookies
- Big Soft Baked Peanut Butter M&M Cookies
- Big Blue Monster Stuffed Cookies
- White Chocolate Biscoff Cookie Butter Cookies
- Kitchen Sink Cookies
Crumbl Copycat Cosmic Brownie Cookies
Ingredients
- 1 cup (227g) salted butter room temperature
- 1 cup (200g) light brown sugar
- ½ cup (100g) granulated sugar
- 2 large eggs
- 2 teaspoons pure vanilla extract
- 2 Tablespoons light corn syrup
- 2 ½ cups (353g) all-purpose flour
- 1 cup Hershey's Special Dark cocoa powder
- 1 teaspoon baking soda
- 1 Tablespoon cornstarch
- ½ teaspoon salt
Ganache
- 1 ½ cups semisweet chocolate chips
- ½ cup heavy cream
- rainbow chip sprinkles
Instructions
- Preheat the oven to 350℉ (177℃). Line baking sheets with parchment paper.
- In a large bowl, beat the butter, brown sugar, and granulated sugar for 2-3 minutes until creamy and light.1 cup (227g) salted butter, 1 cup (200g) light brown sugar, ½ cup (100g) granulated sugar
- Add the eggs and vanilla. Mix again on medium speed until combined, stopping to scrape the bottom and sides of the bowl.2 large eggs, 2 teaspoons pure vanilla extract, 2 Tablespoons light corn syrup
- Add the flour, cocoa powder, cornstarch, baking soda, and salt. Mix on medium-low speed just until combined and no streaks of flour remain.2 ½ cups (353g) all-purpose flour, 1 cup Hershey's Special Dark cocoa powder, 1 teaspoon baking soda, 1 Tablespoon cornstarch, ½ teaspoon salt
- Use a large ¼ cup cookie scoop (4 Tablespoons) to portion the dough into large mounds, then roll them into balls. Press to flatten slightly into pucks roughly ½" thick and space them a few inches apart on the prepared baking sheets, no more than 6 per baking sheet. Bake for 11-12 minutes until set around the edges but do not overbake. The centers may even still look slightly doughy or wet but they will continue to bake and set up on the hot pan. Let cool completely.
- Heat the cream until it bubbles, then pour over the chocolate chips. Let sit for 5 minutes. Stir until smooth.1 ½ cups semisweet chocolate chips, ½ cup heavy cream
- Spoon 1 Tablespoon of the ganache onto each cookie and sprinkle with rainbow chips. Let set up completely in the fridge before serving.rainbow chip sprinkles
Notes
- For smaller cookies, use a 2 Tablespoon scoop and bake for 8-10 minutes.
Storage & Make Ahead
- Store: Store frosted cookies in a single layer in an airtight container at room temperature for up to 3 days. If you need to stack them, place parchment paper between the layers to keep the ganache neat.
- Freeze: Freeze unfrosted cookies in a single layer on a baking sheet, then transfer them to a ziplock bag once solid. They’ll keep for up to 3 months.
- Reheat: Warm a cookie in the microwave for 5-10 seconds for a softer, gooier center. Thaw frozen cookies at room temperature first, then add the ganache.
- Make Ahead: Bake the cookies up to 3 months ahead and freeze them unfrosted. When you’re ready to serve, thaw them, spoon on the ganache, add the rainbow chips, and chill until set.
