Place the sweetened condensed milk, sugar, butter, corn syrup and salt in a large sauce pan. Heat on low and stir until all the sugar has been dissolved. Watch closely so that the mixture does not burn.
Increase the heat to medium and cook in the sauce pan for 3-5 minutes until the mixture has thickened. Watch the mixture closely so it does not burn.
Next, remove the mixture form the heat, stir in the white chocolate melts and continue to stir until all the chocolate chips have melted.
Then transfer the mixture to the prepared pan. Allow the mixture to cool at room temperature and then cover the pan and move the pan to the refrigerator for at least 4 hours.