Some in my family are allergic to various artificial food colors, but my kids really didn't want a white birthday cake cause it is boring.  Beet powder is the perfect coloring for us.  I simply mix it with a small amount of hot water, let it sit a minute, then strain through cheesecloth.  I then use the liquid in making my frosting and it is a beautiful bright pink color--prettier than standard food coloring IMO, and a perfect color for little girls' birthdays.  I have also just added the powder directly to the frosting, which works but it takes a while for the color to appear full strenth and if you look closly you will see tiny dots of beet powder.