3 cups confectioners' sugar
1/2 teaspoon lemon juice
2 tablespoons powered egg whites
6 tablespoons warm water
Pink food coloring
Green food coloring
Blue food coloring
Yellow food coloring
You will also need:
Large resealable plastic bags
Pastry bag fitted with fine tip
Using an electric mixer set on low speed, mix powdered egg whites and warm water until all the water is incorporated, about 2 minutes.
Add the sugar and the lemon juice; mix on high speed until icing is smooth, about 5 minutes (at this point you can just leave the icing white or you may tint some of the icing). Divide icing evenly among 5 bowls. Set aside 1 bowl of icing.
Tint remaining bowls of icing pink, green, blue, and yellow; spoon each color into large resealable plastic bags; snip off one corner for piping.
Using tinted icing, pipe an outline onto each cookie then fill with base color; spread icing evenly. Let icing set until dry.
Place reserved white icing in a pastry bag fitted with a fine tip. Pipe designs on cookies as desired. Let icing set until dry