Ingredients

The following ingredients have 4 Servings
  • 4 TBSP milk (at room temperature)
  • 1 TBSP vanilla extract (or other flavoring)
  • ½ tsp salt
  • 8 oz unsalted butter (at room temperature)
  • 8 oz shortening (can replace with equal amount butter if desired)
  • 28 oz powdered sugar (sifted (7 cups))
  • Gel food coloring in rainbow colors (I recommend Americolor)

Instruction

  • Combine the milk, vanilla extract, and salt in a small bowl, and stir them together to dissolve the salt and set aside.
  • Place the butter in a stand mixer fitted with a paddle attachment. Mix for 2 minutes on medium speed, until the butter is lighter in color and creamy. Scrape the bottom and sides of the bowl.
  • Add the shortening and the milk mixture, and use a splatter guard over your bowl or place a towel over the top of the mixer to prevent splatters. Run the mixer on low until the liquid starts to incorporate, then turn it to medium until everything is well-mixed and smooth (20-30 seconds). Scrape down the bowl again.
  • Keep the towel over the mixer, leaving only a small opening in front, turn the mixer to low, and add the sugar to the bowl in a steady stream. Once all of the sugar is incorporated, scrape down the bottom and sides of the bowl, and turn the mixer to medium-low for 30 seconds to mix the frosting well.
  • Divide the frosting equally between 6 bowls. Add a different color of gel food coloring to each bowl and stir well, adding more if necessary until you get a vibrant color. Place each color of frosting into its own piping bag, and snip a 1/2-inch opening in the end of each bag.
  • Lay out a piece of plastic wrap about 16 inches long. Start by piping a long line of red food coloring on the plastic wrap. Leave a margin of a few inches from the sides and bottom of the wrap.
  • Next, pipe the orange frosting right next to the red, and continue to pipe each color in a line. Depending on how thick you pipe them, you can either fit one line of each color on the wrap, or repeat the pattern and make 12 stripes. Just make sure you leave a margin and don't go all the way to the edge of the plastic wrap. (If you have extra colors left over, you can do this a second time to make another rainbow piping bag.)
  • Now, fold the plastic wrap over lengthwise and roll the frosting into a cylinder. Grasp the ends of the plastic wrap in each hand, and twirl it quickly so the frosting is burrito-shaped and the ends of the plastic are tightly twisted.
  • Fit a piping bag with a large star tip. Snip off one of the plastic wrap “tails," and insert the frosting cylinder into the piping bag, snipped-side down.
  • Squeeze the bag for a moment until all of the colors come out together, then your rainbow piping bag is ready! This recipe makes enough to frost 18 cupcakes with large swirls, or 24-28 cupcakes with small single-layer swirls.