1Preheat oven to 350 degree F. Spray a 15 x 10 sheet cake pan with bakers joy. Or grease and flour.
In a large bowl, combine flour, salt, baking soda, sugar, eggs, and sour cream. Beat on medium with an electric mixer until well blended.
In a medium saucepan, combine the butter, lemon zest, lemon extract, lemon juice and water. Bring to a boil.
Add the lemon mixture to the flour mixture, stir well with a wooden spoon.
Bake for 15 - 18 minutes or until a pick comes out clean. Cool on rack for about 20 minutes.
In a medium saucepan, combine butter, milk and lemon extract and bring to a boil. Remove from heat and gradually whisk in confectioners' sugar until well blended with no lumps. Spread frosting on the cake and cool completely before cutting.