In a small sauce pot, over medium heat, combine raspberries, vanilla, lemon juice, and sugar. Mix well and cook, over medium heat and covered for about 10 minutes. Smash all the berries with a wooden spoon and cook for another 10 minutes over medium-low heat.
Whisk in cornstarch with a little bit of cold water and stir it into the raspberry mixture. Stir for a couple of minutes, until the mixture thickens. You can strain the mixture through a fine strainer to get rid of the seeds and leftover skin or leave it all in.
Set it aside for a few minutes to cool while preparing the cheesecake.
Grease a 9-inch springform pan and set it aside. Preheat the oven to 325°.
Before making the cheesecake, prepare the pan by wrapping outside of the pan in aluminum foil. Many springform pans, especially ones that have been used quite a bit, have a chance of leaking some water inside. Wrapping outside of the springform in foil will help keep water out.
Mix the graham cracker crumbs, sugar, melted butter and vanilla. Stir very well, until all incorporated. Press graham cracker mixture into the pan, evenly, all over the bottom and about half way up the side.
Break up the white chocolate bar into small rectangles and layer them on top of crust, evenly all over the bottom.
Start beating cream cheese and sugar on medium high speed until smooth, about 2 minutes.
Add vanilla extract, and yogurt. Mix until combined.
Add eggs, one at the time, beating after each addition. Scrape sides and bottom of the bowl and beat until all incorporated.
Add corn starch and while on medium low, pour in heavy cream. Mix until all combined, scrape the sides and bottom of the bowl and mix again.
Pour the cheesecake batter into the spring form with crust and spread it out evenly.
Pour raspberry topping slowly and gently over the top of the cheesecake and carefully swirl it into the cheesecake but don't mix.
Place the springform in the oven, inside a large roasting pan. Carefully add some hot water to the roasting pan, filling it about 1/2 of the way up the side of the springform.
Bake for 70-75 minutes. Sides of the cheesecake should be set but still a little jiggle in the center.
Turn off the oven and open the oven door about half way. Let the cheesecake sit there for about 10 minutes and then take the cheesecake pan out of the roasting pan and onto a towel on the counter. Take off the foil from the outside and cool the cheesecake on the counter for about an hour.
Cover top the the cheesecake pan with plastic wrap and refrigerate the cheesecake for at least 6 hours or overnight.
When ready to serve the cheesecake, melt some white chocolate and drizzle it over the top of each slice.