In a small saucepan, whisk together 1 Tbsp granulated sugar and cornstarch until well blended.
Stir in cold water and add raspberries. Cook over medium heat, whisking frequently, until mixture reaches a boil.
Gently boil for about 5 minutes on medium-low heat, whisking constantly until sauce has thickened.
Remove from heat and force sauce through a fine mesh strainer to remove the seeds. Set aside.
Now make the Cheesecake batter:
In a large mixing bowl beat together cream cheese and granulated sugar until smooth and fluffy (about 1 minute).
Beat in the egg and egg white. Add vanilla and lemon juice. Set mixture aside.
Add white chocolate chips and cream to a microwavable bowl.
Microwave on half power, for 30 second intervals, stirring after each interval, until melted and smooth.
Add melted chocolate mixture to cream cheese mixture and stir until smooth.
Pour 3/4 cup cheesecake mixture into the prepared graham cracker crust and spread evenly over bottom.
Drizzle 2 large spoonfuls of the raspberry sauce over the cheesecake batter.
Carefully ladle remaining cheesecake mixture over the drizzled raspberry sauce, making sure to cover all of the raspberry sauce, not allowing it to show through.
Use a toothpick to gently swirl the cheesecake batter smooth. Jiggle the pan gently with your hands to even out the top.
Now you can drizzle the remaining raspberry sauce on top of the cheesecake however you like. (**see recipe notes for heart design)
Bake cheesecake for 40 minutes, then turn oven off and leave the cheesecake in the oven for 5 more minutes.
Remove from oven and allow to cool completely. Cover with tinfoil (or the lid, if using a store-bought crust) and refrigerate for about 6 hours, or until fully set.
Notes
*You could use a store-bought graham cracker crust, or an oreo crust**To make the "heart" design: I used a clean medicine syringe to pipe small circles in a swirl pattern on top of the cheesecake. Then I took a toothpick and, beginning with the center circle, ran it through the center of each circle in the swirl pattern to form hearts. (Make sure not to lift the toothpick out until you finish the last circle).