Homemade Lemon Filling

Ingredients

•  2/3 cups sugar  
•  3-1/2 tablespoons cornstarch 
• 1/8 teaspoon salt 
• 3/4 cup water 
• 1 egg slightly beaten
• 1 tablespoon butter (must be butter kids) 
• 1/4 cup fresh lemon juice 

How to make it 

•  Set up your double-boiler
• Begin by placing water in pot and double boiler bowl on top - make sure the water from pot does not touch bottom of bowl. Turn on heat and let water come to a boil., Then turn heat to a medium, medium low so it simmers.
• Place sugar, cornstarch and salt in double boiler and stir in water with whisk.
• Cook over boiling water until thickened, stirring constantly.
• Once it is thickened, cover with lid and cook an additional ten minutes (and yes stir occasionally - say every three minutes)
• Temper your already slightly beaten egg with some of the hot mixture, then add this slowly back into the remaining hot mixture while stirring constantly.
• Cook over hot (and not boiling) water for 2 minutes, stirring constantly.
• Remove from heat, taking double boiler bowl off and out of the pan that had the water.
• Add butter and stir till butter has melted.
• Chill, once completely cooled, then add the lemon juice and stir.