How to Make Classic Italian Rainbow Cookies (Step-by-Step)

Rainbow cookies with rainbow swirl buttercream frosting for Camille’s birthday!

Camille’s 3rd birthday is coming up and the theme is rainbows: sprinkles, bright colors and lots of cheer. For a kid’s party I prefer decorations that are quick and cheerful — a white icing base makes colors pop, and a swirl of rainbow buttercream is festive without being fussy.

These cookies are simple cut-out sugar cookies iced with a smooth, small-batch royal icing and finished with a rainbow swirl buttercream. The royal icing dries to a firm, matte white surface that provides a clean canvas for the colorful piped rainbows.

Overview

I make a small batch of cut-out sugar cookies and top them with a simple royal icing (one egg white, powdered sugar and lemon). That royal icing spreads easily with the back of a knife and sets without running over the edges, so it’s a low-maintenance base when you don’t want to pipe a border. Once the royal icing has fully hardened, I pipe small rainbow arches in buttercream and finish each with gold sprinkles and a few gold dragees.

Making the Buttercream Rainbow

I make a small batch of plain buttercream (one stick of butter; this amount covers about 11–12 cookies). Divide the frosting into six bowls and tint them red, orange, yellow, green, blue and purple. On a square of plastic wrap, pipe long, narrow stripes of each color in rainbow order. Roll the plastic wrap into a tube, twist the ends, snip one end, and place the wrapped tube inside a piping bag fitted with a round tip. When you pipe, the colors come out together in a pretty rainbow swirl.

Decoration Tips

• Spread the royal icing almost to the cookie edges with an offset spatula and allow it to harden completely before piping buttercream.
• Pipe small rainbows on one end of each cookie. A practice rainbow on scrap paper helps you get consistent size and spacing.
• Finish each rainbow with a pinch of gold sprinkles and a couple of gold dragees for a little shine.
• This method is forgiving: the white royal icing hides small imperfections and makes the colors look crisp and clean.

Yield and Uses

This recipe yields about 11 cookies — a perfect small batch for party favor bags. I often end up with more buttercream than I need; the frosting recipe makes about twice as much as required for these cookies, which is convenient if you want to frost a small cake too. If you don’t want leftovers, halve the frosting quantities.

Instructions (Summary)

1. Make a small batch of cut-out sugar cookies and chill the cut shapes before baking.
2. Bake cookies at 350°F for about 10–12 minutes until edges just begin to brown; cool completely.
3. Prepare a small-batch royal icing: combine powdered sugar and lemon juice, add 2 Tbsp beaten egg white, whisk slowly until smooth, then spread onto cooled cookies and let harden.
4. Make buttercream with one stick of butter, powdered sugar, a tablespoon of heavy cream and vanilla; beat until light and fluffy.
5. Divide into six bowls and color each one red, orange, yellow, green, blue and purple using gel food coloring.
6. Pipe narrow stripes of frosting onto plastic wrap, roll into a tube, snip one end and place inside a piping bag fitted with a round tip, then pipe rainbows onto the iced cookies.
7. Add gold sprinkles and gold dragees to the ends of each rainbow.

These cookies will go in Camille’s goody bags — I’m excited to share them at her party. They’re bright, cheerful, and straightforward to make when you want a festive treat without spending hours on decoration.

Yield: 11

Rainbow Cookies

Rainbow cookies with rainbow swirl buttercream frosting!

Prep Time
1 hour

Cook Time
12 minutes

Total Time
1 hour 12 minutes

Ingredients

Cookies

• 3/4 cup flour, plus extra for rolling
• 1/2 teaspoon baking powder
• Pinch of salt
• 1/4 cup unsalted butter, softened
• 1/4 cup sugar
• 1 egg yolk
• 1/2 teaspoon vanilla
• 1/4 teaspoon almond extract

Small-batch royal icing

• 1 1/2 cups powdered sugar
• 2 teaspoons fresh lemon juice
• 1 large egg white (use about 2 tablespoons)

Rainbow buttercream

• 1 stick unsalted butter, softened
• 2 1/2 cups powdered sugar
• 1 tablespoon heavy cream
• 1 teaspoon vanilla extract
• Red, yellow and blue gel food coloring (to mix orange, green and purple)

Instructions

1. Whisk flour, baking powder and salt together.
2. Beat butter and sugar until light, add egg yolk and extracts.
3. Fold in flour mixture in two additions until combined; avoid over-mixing.
4. Roll dough to 1/2″ thick and cut 4″ rounds (about 11–12 cookies). Chill briefly.
5. Bake at 350°F for 10–12 minutes until edges just color; cool on a rack.
6. Make royal icing: combine powdered sugar and lemon juice. Add 2 tablespoons beaten egg white and whisk slowly until smooth. Spread on cookies and let harden fully.
7. Make buttercream: beat butter, powdered sugar, cream and vanilla until light. Divide into six bowls and tint colors.
8. Pipe colored stripes onto plastic wrap, roll into a tube, snip one end and place into a piping bag with a round tip. Practice, then pipe rainbows on the iced cookies.
9. Finish with gold sprinkles and dragees at the rainbow ends.

Notes

The frosting recipe makes more than needed for these cookies; you can halve the buttercream if you prefer to avoid leftovers.

Nutrition Information (per serving)

Calories: 333 • Total Fat: 14g • Saturated Fat: 8g • Cholesterol: 68mg • Sodium: 45mg • Carbohydrates: 51g • Sugar: 44g • Protein: 2g