In a large mixer bowl, combine 1 1/4 cup sugar, 5 egg whites and flavoring. Heat over a pot of simmering water. Wisk for 3 minutes.
Whip on high for three minutes using the wisk attachment.
When frosting is thick, add 4 sticks of butter, a tablespoon at a time. Using the paddle attachment, mix until blended. Add food coloring and frost your cake.
This recipe makes a lot, so I usually only make half the recipe, which frosts one cake.