Butter 13 x 9 inch Pyrex dish and line with graham crackers (NOT crushed). Mix together pudding and 3 cups milk; fold in Cool Whip. Pour half of this mixture over graham crackers. Place another layer of graham crackers over this and pour rest of the pudding mixture over crackers. Lay a third layer of graham crackers on top. Frost top layer with fudge frosting and let set all day or night in the refrigerator.
For frosting, combine sugar, salt, cocoa, 1/4 cup milk and corn syrup. Heat slowly; bring to a boil and cook 1 minute. Remove from heat. Add butter and vanilla. Cool. Beat until smooth and spread over crackers. If you wish, use your own fudge frosting with powdered sugar.
