Preheat your oven to 325°F (160°C). In a medium bowl, mix together graham cracker crumbs, granulated sugar, and melted butter until the mixture resembles wet sand. Press this mixture firmly into the bottom of a 9-inch springform pan, ensuring an even layer. Bake for 8 minutes, then allow it to cool completely before adding the cheesecake filling.

In a saucepan over medium heat, combine fresh or frozen raspberries, sugar, and lemon juice. Cook for about 5-7 minutes, stirring occasionally, until the mixture thickens and becomes syrupy. Once done, remove from heat and let it cool to room temperature.

Roughly chop high-quality white chocolate and place it in a microwave-safe bowl or double boiler. Heat it gently, stirring every 20 seconds in the microwave or continuously on the stove until entirely melted and smooth. Allow the melted chocolate to cool slightly.

In a large mixing bowl, beat cream cheese and granulated sugar until creamy and smooth, which should take about 3-4 minutes. Add eggs one at a time, mixing well after each addition. Stir in vanilla extract, sour cream, and heavy cream until combined, then gently fold in the slightly cooled melted white chocolate.

Pour half of the cheesecake batter over the cooled crust in the springform pan. Drizzle raspberry sauce over the batter and use a knife to create swirls. Top with the remaining batter and repeat with raspberry sauce, swirling again.

Prepare a water bath by placing the springform pan inside a larger baking dish filled with hot water. Bake in the preheated oven for 60-70 minutes, or until the edges are set while the center jiggles slightly.

Once baked, turn off the oven and let the cheesecake cool slowly inside with the door ajar for about 1 hour. Afterward, refrigerate for at least 4 hours or preferably overnight.

Before serving, garnish each slice with extra raspberry sauce or fresh berries.