In a large bowl, beat cream cheese and confectioners' sugar until smooth. Fold in whipped topping; set aside. Cut cake horizontally into two layers. Place the bottom layer on a serving plate; spread with cream cheese mixture. Replace top; refrigerate.
In a saucepan, combine 3/4 cup of cream, sugar, corn syrup, butter and salt. Cook and stir until mixture reaches soft-ball stage (234°). Slowly add remaining cream. Cook and stir until mixture returns to soft-ball stage (234°). Remove from the heat; stir in vanilla. Cool. Drizzle over cake. Store in the refrigerator. Yield: 12 servings.