Sift the dry ingredients

• Sift the powdered sugar into a mixing bowl.
• Add the cornstarch and stir it in so it doesn't stick to the spoon.

Beat the icing

• Add the egg whites and mix everything together until the icing is nice and stiff.

Rest the icing

• Cover the bowl with a damp paper towel to keep the icing from drying out.

Make the stiff consistency

• Transfer some of the icing to a bowl and tint it with food coloring.
• Mix until it reaches a toothpaste-like consistency that doesn't fall or merge back together when shaken.
• Transfer to a piping bag and tie it off.

Make the flood consistency

• Thin another portion of icing with a little water until creamy and pourable.
• It should blend back together smoothly when the bowl is shaken.
• Transfer to a piping bag.

Outline the cookies

• Cut a very small tip on the stiff-consistency bag.
• Pipe the borders and lettering slowly around the cookie.

Flood the cookies

• Cut a slightly bigger hole in the flood-consistency bag.
• Fill from the outside in, then shake gently so the icing reaches the edges.
• Add a little more icing where it doesn't reach and pop air bubbles with a toothpick.

Dry the icing

• Let the decorated cookies dry overnight or for at least 8 hours.