Yellow Food Coloring - Optional - I do not use this. I don't need the frosting to be bright yellowbut some people like that look. If you want the bright yellow look, add about 4 drops of food coloring.
Start by making the lemon pie filling. Once it is done, let it cool.
When the filling is cool, combine the filling with the thawed Cool Whip.
Then the frosting is ready to be used on a cake or cupcakes.