Mix the eggs, cream of tartar, and powdered sugar on medium speed for four minutes. If the icing can't form peaks, add 1/4 cup of powdered sugar in increments until it does.
Find a picture of Princess Peach that you like and print it out. Tape it to a large cookie sheet and cover the picture with a sheet of wax paper, and tape that down as well.
Split the icing in half. Add several drops of yellow gel food coloring to one half and mix well.
Spoon 1/8th of the remaining icing into a bowl and add several drops of pink gel food coloring. To 2 Tbsp of the remaining icing, add the black food coloring. With the last 4 Tbsps of icing, make each a different color: orange, blue, and red, leaving the last Tbsp white.
Using a small pastry bag tip, outline the image with the black icing, then fill in the hair with yellow and allow to dry for 30 minutes.
Fill in the face with pink and let dry for another 30 minutes before adding the facial features in black icing.
Fill in the crown with orange and let dry. Add the red and blue jewels to the crown and fill in the earring with white.
Allow to dry for 5-10 hours, then peel the wax paper off the back of them and place on the frosted cupcake.