1cup(227g) unsalted buttersoftened to room temperature
4 to 5cups(480-600g) powdered sugar
¼ to ⅓cup(60-80mL) milk or cream
2teaspoonsvanilla extract
¼teaspoonsalt
Instructions
RAINBOW CHIPS
Prepare a large baking sheet with parchment paper or a silicone baking mat. Set aside.
Set out 4 small bowls and 4 spoons or spatulas for each color of white chocolate (or however many colors you'd like to make-- do not make more than 4 colors). Set aside.
Use a double boiler, a small saucepan over medium-low heat on the stove, or the microwave to melt the white chocolate. Melt it slowly, as white chocolate has a tendency to seize, and stir excessively through the process to distribute the heat and prevent hot spots.
When your white chocolate is fully melted, pour about 1 ounce into each of the prepared separate bowls.
Working with one bowl and color at a time, add a tiny bit of coloring to one portion of melted white chocolate, then stir to distribute the color. If the white chocolate seizes, do not panic. Add a few drops of vegetable oil, canola oil, or other neutral oil or about ¼ teaspoon of vegetable shortening and stir to smooth it out again.
Once the chocolate is colored, spread it into a thin, even layer on the prepared baking sheet. Each of my rectangles were about 6" x 4" but this does not need to be a perfect measurement.
Repeat with remaining colors, then place in the refrigerator to chill while you prepare the frosting.
In a medium size bowl with a handheld mixer or a stand mixer fitted with the paddle attachment, beat the the butter on medium-high until smooth.
Turn the mixer to low, then slowly add the powdered sugar and mix until everything is combined. Add the vanilla extract, milk or cream, and salt, increase the mixer speed to medium and beat until combined. Turn off the mixer and use a spatula to stir the buttercream by hand to remove air bubbles and make it smooth and creamy. This usually takes about 3-5 minutes.
When your buttercream is smooth, cover it and set it aside.
Remove the colored white chocolate from the refrigerator, and chop each color into very small pieces to create rainbow chips.
Once you have all of the chips chopped, mix them together, then add desired amount3 to the vanilla buttercream. Use on your favorite cake or cupcakes or my favorite, on my funfetti cinnamon rolls! Store leftovers at room temperature up to 3 days, or in the refrigerator or freezer up to 3 months. Keep in mind that the color may bleed as the frosting sits.
Notes
White chocolate: it is imperative that you use quality white chocolate like bar baking chocolate or vanilla melting wafers. I do not recommend using candy melts or white chocolate chips for this.
Food coloring: I prefer gel food coloring and my favorite brand is AmeriColor.
Add chips to frosting: you will wind up with about 1 cup of chopped colored white chocolate, and this homemade rainbow chip frosting has the best distribution of chips with about ¾ cup of the chips. In my experience, adding in the very tiny flecks that come with chopping any kind of chocolate tend to bleed into the white frosting because they start to dissolve with the moisture of the frosting. Try to leave those tiny pieces out and keep them in the ¼ cup of chips you don't add to the frosting but rather use for sprinkling on top of the frosting like you would sprinkles.
All nutritional values are approximate and provided to the reader as a courtesy. Changing ingredients and/or quantities will alter the estimated nutritional calculations.