01 - Preheat oven to 325°F. Line a 9x9-inch baking pan with parchment paper, ensuring an overhang for easy removal.
02 - Combine graham cracker crumbs, granulated sugar, and melted butter in a medium bowl. Press mixture firmly and evenly into the base of the lined pan to create a smooth crust layer.
03 - In a large bowl, beat softened cream cheese and sugar using an electric mixer until smooth. Add eggs one at a time, mixing thoroughly after each addition. Blend in vanilla extract and sour cream until mixture is fully combined and creamy.
04 - Pour cheesecake filling over prepared crust, spreading evenly to corners. Bake for 40 to 45 minutes, or until center is just set and edges are lightly golden.
05 - Remove pan from oven and allow cheesecake to cool to room temperature. Refrigerate for at least 3 hours to set completely.
06 - Once chilled, evenly distribute chopped strawberries and blueberries over the surface to create a festive pattern. Drizzle with melted white chocolate if desired. Slice into bars and serve chilled.