In microwave-safe bowl,melt white chocolate and butter at 70% power;stir until smooth.Cool.
In a larger bowl, beat eggs and sugar until lemon-colored.Beat in melted chocolate mixture and vanilla.Combine flour and salt;beat into egg mixture.Spread into a greased 9x13 inch baking dish;set aside.
For filling,in a small bowl,beat cream cheese and white chocolate,beat in the egg,sugar,sour cream and vanilla just until combined. Carefully spread over bottom-layer.Cut through filling with a knife to swirl.
Bake at 350* for 40-45 minutes or until a toothpick inserted near the center comes out clean.Cool on a wire rack.
Just before serving,fold whipped cream into white chocolate.Fold in strawberries;spread over dessert. Cut into squares.Refrigeratate leftovers.