These fudgy cosmic brownie cookies are your favorite nostalgic treat but in cookie form! Each chocolate cookie is super fudgy and rich, topped with homemade chocolate ganache and rainbow chips. This is such a fun take on a childhood classic!

Save This Recipe! 💌
Who else remembers Little Debbie Cosmic Brownies? If you put rainbow chips on something, I 100% will want to eat it! These cosmic brownie cookies are a fun take on cosmic brownies, but homemade.
I'm using my favorite chocolate cookie base (the same one from my chocolate s'mores cookies and one bowl triple chocolate chunk cookies!) and topped them with a simple homemade chocolate ganache and rainbow chocolate chips.
The JOURNEY I went through trying to find these chips, let me tell you! I ended up having them shipped to my hotel room the last time I was in New York because I just could not find them here in London! Worth it.
Why I love this recipe!
- Super Easy - you just need 2 bowls (one for the cookie dough, one for the chocolate ganache) to make these cosmic brownie cookies!
- Chocolate Lovers - if you are a chocolate lover, then you have to try this recipe.
- Rich & Fudgy - these chocolate cookies are super fudgy, no dry cookies here.
Grab Your Ingredients!

- Cocoa Powder: I've only tested this recipe with Dutch processed cocoa powder and not natural unsweetened cocoa powder. I don't recommend swapping it out because they react differently to baking soda and baking powder. Not sure if the cocoa powder in your pantry is dutch processed? Check the ingredients! If it says 'alkali' or 'acidity regulators', then it's dutch processed cocoa powder.
- Butter: I'm always a fan of using European butter! Why? It has a higher percentage of butterfat, making whatever you bake with it creamier and richer.
- Chocolate: I recommend using semi-sweet or dark chocolate to make the chocolate ganache.
- Rainbow Chips: these are the rainbow chips I used, but if you can't find them then swap them out for mini chocolate chips or rainbow sprinkles!
- Heavy Cream: You'll need to use heavy cream (or double cream if you're in the UK) to make the ganache.
Let's Make This Recipe!

Step 1: In your stand mixer or large bowl with a hand mixer, mix the butter, granulated sugar and light brown sugar until light and fluffy. Add the vanilla extract, egg and egg yolk.

Step 2: Mix in the flour, cocoa powder, salt, baking powder and baking soda. Mix until just combined. Chill the cookie dough in the fridge for 30-60 minutes, this will help them not spread as much when baking.

Step 3: Preheat your oven to 350ºFahrenheit and line two baking sheets with parchment paper. Scoop out 3 tablespoons of cookie dough and place on the prepared baking sheets.

Step 4: Bake in the oven for 8-10 minutes. Let the cookies cool for 5 minutes on the baking sheet before removing to a wire cooling rack to cool completely.

Step 5: Place the chopped chocolate in a bowl. Heat the cream in a medium saucepan on the stove until it beings to steam and simmer. Pour over the chocolate and let sit for a few minutes.

Step 6: Use a rubber spatula to gently stir in one direction until completely smooth. If you still have chocolate chunks, place in the microwave in 10-second increments. Use a spoon to spoon over the cooled cookies, and a small offset spatula to spread it over the cookies. Top with rainbow chocolate chips and enjoy!

Ella's Tips & Tricks
- Kitchen Scale: I always, always recommend using a kitchen scale when baking! Otherwise, it's so easy to add too much cocoa powder or flour, which are going to give you cookies that are as dry as the desert.
- Let the Cookies Cool: make sure the cookies are completely cool before you add the ganache topping, or it might melt right off!
- Swap out Rainbow Chips: if you can't find rainbow chips, top them with mini chocolate chips, baking chips in another flavor (how amazing would peanut butter chips be?), sprinkles, crushed candy canes, or flaky sea salt!
- Heat the Heavy Cream: Make sure you don't let the heavy cream come to a boil. If it's too hot when it's poured over the chopped chocolate, it's going to give you a grainy chocolate ganache.

Try these chocolate cookies next!

Made This Recipe?
Make sure to leave a ⭐️ rating and review below! You can tag me on Instagram @alpineella or follow along on Pinterest, Facebook and TikTok!
Thank you!
Ella
Recipe

Cosmic Brownie Cookies
Ingredients
Cookies
- ½ cup (113 grams) unsalted butter room temperature
- ½ cup (100 grams) white sugar
- ½ cup (105 grams) light brown sugar
- 1 large (1) egg room temperature
- 1 large egg yolk room temperature
- 1 teaspoon (1 teaspoon) vanilla extract
- 1 teaspoon (1 teaspoon) kosher salt
- 1 ¾ cups (210 grams) all purpose flour
- ½ teaspoon baking powder
- 1 teaspoon baking soda
- ⅓ cup (29 grams) dutch processed cocoa powder
Chocolate Ganache
- ⅔ cup (70 ml) Heavy Cream
- 3.7 oz (106 grams) Semisweet Chocolate chopped
- Rainbow Chips
Instructions
- In a stand mixer fitted with the paddle attachment, or in a large bowl with a hand mixer, beat the butter with the sugar and light brown sugar for 2 minutes. It should be light, fluffy, and have turned a slightly paler color.½ cup (113 grams) unsalted butter, ½ cup (100 grams) white sugar, ½ cup (105 grams) light brown sugar
- Stop the mixer and use a rubber spatula to scrape the sides and bottom of the bowl. Add the egg, egg yolk and vanilla extract, then beat again on medium speed for 1 minute until combined.1 large (1) egg, 1 teaspoon (1 teaspoon) vanilla extract, 1 large egg yolk
- Stop the mixer and add all of your dry ingredients - flour, baking powder, baking soda, salt and cocoa powder. Beat on low speed so the dry ingredients don't go flying out! Make sure to stop the mixer and scrape the sides and bottom of the bowl again so everything gets mixed together.1 teaspoon kosher salt, 1 ¾ cups (210 grams) all purpose flour, ½ teaspoon baking powder, 1 teaspoon baking soda, ⅓ cup (29 grams) dutch processed cocoa powder
- Place in the fridge for 45-60 minutes - note this is a sticky dough so the chilling will help with scooping!
- Preheat the oven to 350°Fahrenheit/175°Celsius and line 2 baking sheets with parchment paper.
- Scoop out 3 heaping tablespoons of dough cookie and place them on the prepared baking sheet.
- Bake the cookies for 8-10 minutes. While one sheet is baking, I place the other sheet in the fridge.
- Let the cookies cool on the baking sheet completely before moving to the next step.
- Place the chopped chocolate in a large bowl.3.7 oz (106 grams) Semisweet Chocolate
- Heat the heavy cream in a saucepan over medium-low heat or microwave until it simmers. Make sure it does not boil!⅔ cup (70 ml) Heavy Cream
- Pour the hot heavy cream over the chopped chocolate and sit for 5 minutes.
- Stir the chocolate and cream mixture with a rubber spatula until completely smooth. If it still has pieces of chocolate, place it in the microwave in 10-second increments, stirring after each one gently, until melted.
- Spoon the ganache over the cooled chocolate cookies and use a small offset spatula to spread it over the cookies. Immediately sprinkle over the rainbow chips. Let the ganache set before enjoying.Rainbow Chips













Leave a Reply