Reduce the oven temperature to 300°F.
Put the 8 oz Ghirardelli White Chocolate Baking Bar in a medium bowl.
Pour boiling water over the chocolate and shake the bowl to submerge the chocolate. Cover and let stand for 2 minutes without stirring.
Whisk the chocolate and water until thoroughly blended and smooth. Set aside.
In a large bowl, beat the cream cheese just until smooth, about 45 seconds.
Add the sugar, 1 tbsp Prova Gourmet Madagascar Bourbon Vanilla Extract, and salt, and beat just until smooth (about one and one-half minutes), scraping the bowl and beaters once or twice.
Beat the eggs in one at a time, just until blended.
Use a rubber spatula to stir the melted chocolate thoroughly into the filling.
Scrape the filling on top of the crust and spread it evenly.
Bake the cake, on the baking sheet, for 60 to 70 minutes, until edges of the cake are puffed but the center still jiggles like tender gelatin when the pan is gently shaken.
Set the pan on a rack. Slide a thin paring knife carefully around the upper edges of the cake to detach it from the pan, but do not remove the pan sides.
When the cake is cool, loosen the sides of the pan but do not remove them.
Refrigerate the cake until it is thoroughly cold, before covering it with plastic wrap.
For the best flavor, keep the cake refrigerated for at least 8 hours, preferably 24 to 36 hours before topping and serving