Ever wondered how to make those beautifully swirled rainbow frosting cupcakes? It’s a lot easier than it looks! Find out how with my easy Rainbow Frosting Tutorial!

You’ve seen them on Pinterest and Instagram and wondered how they make those pretty rainbow swirl cupcakes right? It’s actually a lot easier than you think with my easy to follow frosting guide.

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Rainbow Frosting Cupcakes

Have you looked at pictures of rainbow swirl cupcakes and cakes and wondered how the heck they did that? Well, my Party Princess friends, it’s really easy and you can totally do this! I made these rainbow cupcakes for a Trolls photo shoot I did years ago and can’t believe I never shared this frosting hack.

Before we get started here is what you need:

How to Make Rainbow Swirl Cupcakes

To make this classic rainbow swirl buttercream frosting you will need:

Powdered sugar
Milk
Meringue powder
Vanilla extract
Salt
Unsalted butter (you can also use Sweetex if you prefer)

You can find my tried and true buttercream frosting recipe below. After you have made your buttercream frosting, divide frosting evenly into bowls. I chose five colors for these cupcakes so I divided the frosting into five bowls. Next, slowly add food coloring, one drop at a time, until you get the desired color. Spoon buttercream into disposable pastry bags.

Pro Tip: Pastry bag ties are really helpful! I didn’t have them when I made these rainbow icing cupcakes but I highly recommend them.

I did not use decorating tips since I wasn’t going to actually be decorating the cupcakes, I was only piping lines. You can easily snip the ends of the bags or if you prefer, drop the tips in the bags before filling with frosting.

Now that your bags are loaded with frosting, pipe frosting line by line on a large sheet of plastic wrap. I wouldn’t do more than two lines of each color.

Rainbow Swirl Frosting

Carefully roll the plastic wrap so it looks like a sausage then twist the ends.

I don’t have a picture of the next step, but once your frosting roll is ready, prepare your 16″ pastry bag. Choose your preferred decorating tip and drop in decorating bag.

Next, snip one end of the frosting roll and place in bag, snipped end down. For the cupcakes below, I used an 8mm round. Don’t forget to use the coupler too. If you want a “ruffled” look use a star tip.

Starting at outer edge, pipe around the top of the cupcake working your way towards the middle. I go around three times.

Once you have decorated all of your cupcakes, sprinkle some edible glitter on them and serve on a pretty platter.

These would be perfect for rainbow unicorn cupcakes, St Patrick’s Day, or even a Pride event.

How do you swirl two colors of icing?

If you just want two colors instead of multiple like these rainbow cupcakes, you can put two piping bags in the bigger pastry bag and swirl as described above.

How do you decorate cupcakes without a piping bag?

Ziploc bags make great decorating bags! Fold the top over, fill with frosting, twist or seal the bag, and the snip one of the corners. Start with just a small snip and trim bigger if necessary.

Classic Buttercream Frosting Recipe

Classic Buttercream Frosting

Name: Classic Buttercream Frosting
Prep time: 10 min
Total time: 25 min
Cuisine: American
Ingredients: 1.5 cups unsalted butter, room temperature; 1/4 tsp salt; 1 tsp meringue powder; 2 lbs powdered sugar, sifted; 1/2 cup milk; 1 tsp vanilla extract

Prep Time: 10 minutes

Additional Time: 15 minutes

Total Time: 25 minutes

Use this classic buttercream frosting to decorate cakes, cupcakes, brownies, and cookies.

Ingredients

1.5 cups unsalted butter, room temperature
1/4 tsp salt
1 tsp meringue powder
2 lbs powdered sugar, sifted
1/2 cup milk
1 tsp vanilla extract

Instructions

Mix butter, salt, and meringue powder with a hand mixer or in a standing mixer
Slowly add milk then add powdered sugar one cup at a time on low.
Scrape down sides of bowl
Add vanilla extract
Increase power to medium and beat for 2-5 minutes until smooth and fluffy. Will take about 2 minutes with a standing mixer and about 5 with a hand mixer.
If mixture is too thick, add milk one tsp at a time until desired consistency is achieved.
If mixture is too thin, add powdered sugar 1/4 cup at a time.
Do not over beat the frosting as it will break down the fat from the butter. If this happens your frosting will not set properly and likely be too runny. Your buttercream frosting should be smooth and a little stiff.
This recipe makes enough to ice a 2 layer 9x13 cake, 3 layer 6" round cake, or 2 dozen cupcakes.

Notes

Always add salt as this helps cut the sweetness. You can find meringue powder at Walmart, Michael's, Hobby Lobby, Joann's, and cake supply shops. If you buy the 2 pound bag of powdered sugar you don't have to worry about sifting.