The Best Rainbow Chip Buttermilk Brownies Recipe

These Rainbow Chip Brownies are homemade buttermilk brownies at their best. Made from scratch and topped with colorful candy sprinkles, these brownies look like Little Debbie’s Cosmic Brownies but taste worlds better!

There’s no such thing as too many brownies. From decadent Oreo Brownies to Chocolate Chip Zucchini Brownies–I’ve never met a brownie I didn’t like.

These Rainbow Chip Brownies are made using the best homemade buttermilk brownie recipe! Move over Cosmic Brownies from Little Debbie...these are too delicious to compare!

Why this Recipe is Best

Know what makes me extra happy? A hot cup of coffee and one of these Rainbow Chip Brownies.

  • A childhood classic!
  • Inspired by Cosmic Brownies from Little Debbie.
  • Based on my favorite Buttermilk Brownie recipe.
  • Rich homemade chocolate frosting.
  • Sprinkled with Rainbow Chips!

No offense to Debbie and her baking skills but the packaged brownies I used to get in my lunch box just don’t hold a candle to these homemade brownies with rainbow chips.

I also have a homemade oatmeal cream pie recipe if you’re looking more more copycat recipes for nostalgic treats.

These Rainbow Chip Brownies are made using the best homemade buttermilk brownie recipe! Move over Cosmic Brownies from Little Debbie...these are too delicious to compare!

Ingredient Notes

Rainbow chips are not just any sprinkles. They’re little pieces of chocolate in a hard candy coating! I love them on brownies and they’re AWESOME mixed into frosting or cake batter too.

Buttermilk is the secret to amazingly moist brownies. It’s used in both the brownie batter and the frosting so the rainbow chip brownies stay soft and moist, even a few days after baking! Use our easy buttermilk substitute for a quick fix.

Dark chocolate cocoa powder tastes best in these brownies. Use a high quality brand like Rodelle or Ghirardelli if you can. Trust me–it makes a difference.

Easy Instructions

PRO TIP: Don’t have buttermilk? Make my easy buttermilk substitute with just milk and lemon juice (or white vinegar)!

Prepare the brownie batter:

Bring butter, cocoa powder and vegetable oil to a boil, then add it to a mixing bowl with eggs, buttermilk, sugar and vanilla. Gently stir in the dry ingredients to form a batter.


Pour the batter into a parchment lined baking dish. Bake for 20 minutes and let the brownies cool.


Combine all the frosting ingredients, except for the powdered sugar, in a sauce pan. Bring to a boil over medium heat whisking constantly. Pour the butter mixture into a bowl with the powdered sugar. Beat until the frosting is smooth and combined.

Spread the frosting over cooled brownies. Finally, sprinkle rainbow chips on top! w

Tips and Tricks

  • Chill the brownies before cutting. These taste extra delicious served cold straight out of the fridge!
  • Bake in a 13 x 9 baking dish. You’ll have plenty of thick, moist brownies to go around.
  • How to store brownies: Stored in the fridge, rainbow chip brownies stay good for about 1 week. For longer storage, you can freeze them.

Recipe FAQs

Where can I buy rainbow chips?

You can find rainbow chips in the baking aisle at your grocery store. They’re usually near the chocolate chips. Or buy them online!

Should I freeze brownies with or without the frosting?

It’s up to you. To freeze frosting brownies, place a piece of wax paper over the frosting first. This prevents the frosting from becoming runny and goopy as it thaws.

How do you cut brownies evenly?

A plastic knife works best for cutting brownies evenly without tearing or sticking. Make sure to wipe the knife clean after every cut for smooth, even edges.
Also: Do not skip the chilling! If you don’t chill these rainbow chip brownies, they’ll fall apart and get gooey when you try to cut them.

More Brownie Recipes

More Easy Dessert Recipes

Rainbow Chip Brownies

5 from 1 vote
By: Aimee
These Rainbow Chip Brownies are made using the best homemade buttermilk brownie recipe! Move over Cosmic Brownies from Little Debbie…these are too delicious to compare!
Prep Time: 5 minutes
Cook Time: 20 minutes
Additional Time: 2 hours
Total Time: 2 hours 25 minutes
Servings: 40 small bars


For the Brownies:

  • ½ cup unsalted butter
  • ¼ cup dark chocolate unsweetened cocoa powder
  • ½ cup vegetable oil
  • 2 cups granulated sugar
  • 2 large eggs
  • ¼ cup buttermilk
  • ½ teaspoon vanilla extract
  • 2 cups all-purpose flour
  • 1 teaspoon baking soda
  • ½ teaspoon kosher salt
  • 1 cup semi-sweet chocolate morsels

For the Frosting:

  • ½ cup unsalted butter
  • ½ cup buttermilk
  • ¼ cup dark chocolate unsweetened cocoa powder
  • 4 cups powdered sugar
  • 1 cup rainbow chips


  • Preheat oven to 400F. Line a 13×9-inch baking dish with parchment paper. Set aside.
  • For the brownies, in a small saucepan over medium high heat, combine butter, cocoa powder and oil. Bring to a boil and remove from heat.
  • In a large mixing bowl, combine granulated sugar, eggs, buttermilk and vanilla. Slowly whisk in the butter mixture. Add in flour, baking soda, and salt. Stir just until combined. Fold in chocolate chips.
  • Pour into prepared baking dish and bake for 20 minutes. Remove from oven and cool.
  • While cooling, prepare the frosting. Combine butter, buttermilk and cocoa powder in a small saucepan. Whisk over medium heat until mixture begins to boil. Remove from heat.
  • In a mixing bowl, combine powdered sugar with butter mixture. Beat for several minutes until smooth. Pour over brownies. Sprinkle immediately with rainbow chips!
  • Refrigerate for about 2 hours, until set. Cut and enjoy. I store these in the refrigerator for best results!


Serving: 1, Calories: 219kcal, Carbohydrates: 31g, Protein: 2g, Fat: 10g, Saturated Fat: 5g, Polyunsaturated Fat: 5g, Cholesterol: 22mg, Sodium: 82mg, Fiber: 1g, Sugar: 25g
Course: Brownies and Bars
Cuisine: American
Did you make this recipe?Mention @shugarysweets or tag #shugarysweets!
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About Aimee

Aimee is a dessert lover (specifically rice krispie treats), workout enthusiast, self-taught foodie, and recipe creator.

Learn more about Aimee.

Affiliate Disclosure:**There may be affiliate links in this post! By clicking on them, or purchasing recommended items I may receive a small compensation. However, I only recommend products I love! Thank you for supporting Shugary Sweets! See my disclosure policy for more info**

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Posted on March 1, 2019

Comments & Reviews

  1. Ooo Buttermilk brownies! Never made them with buttermilk, but they look so delish. And I am SOOOOO jealous your weather has changed, still 85-90F here in So Cal… still hating turning the oven on!! 

  2. I’m not happy about the sudden cold snap, either, and I’m not even in Chicago. I used to go there all the time. I love the pizza! Miss it lots and lots.
    These brownies are so happy. They might drive the chill away!

  3. I think that’s just human nature right? When we are hot we complain…when we are cold we complain…why can’t it just be 72 degrees all the time?? 🙂 At least we have rainbow chip brownies to make ourselves feel better 🙂

  4. These are so happy-making!  I have not ever seen Rainbow Chips; good golly, all I’ve been missing.  Oh good, I just noticed Lauren above hasn’t seen them either.  Thanks for the delish reicpe, weather update and the happy post.

  5. I have never seen rainbow chips before! Just in time for my kids’ birthday cakes! And of course these amazing brownies!

  6. Thanks for the brownie linky love 🙂 And yes Chicago weather is like that, it goes from hot to cold, overnight. None of those nice ‘fall’ days. It’ll be snowing next week. lol

    I have never made brownies with buttermilk! I’ve tried a gazillion brownie recipes, but never with buttermilk. Now I think I have to!

  7. These brownies are just making me smile right now. Adorable.

    Your weather situation in Chicago sounds a lot like Buffalo. This year, we went fro high 80’s to what feels like frigid weather. No sun. Rain. Can’t even mow the lawn. Hope our neighbors aren’t mad! Oh well, I’ll just make these brownies instead. Would you consider liking the bowl a workout? No. How about whipping around that spatula?

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