01 - Preheat oven to 325°F. Line a 9x9-inch baking pan with parchment paper, allowing excess to hang over the sides for easy removal.
02 - Combine graham cracker crumbs, granulated sugar, and melted butter in a medium bowl. Press the mixture evenly into the bottom of the prepared pan to create a compact layer.
03 - Using an electric mixer, beat cream cheese and sugar in a large bowl until smooth. Add eggs one at a time, mixing thoroughly after each addition. Blend in vanilla extract and sour cream until the batter is creamy and homogenous.
04 - Spread the cheesecake filling evenly over the prepared crust using a spatula.
05 - Bake on the center rack for 40 to 45 minutes, or until the center is just set and edges are lightly golden. Remove from oven and cool to room temperature.
06 - Transfer the cooled pan to the refrigerator and chill for a minimum of 3 hours until fully set.
07 - Top chilled cheesecake with an even layer of chopped strawberries and blueberries, arranging them for a festive appearance.
08 - If desired, drizzle melted white chocolate over the fruit in decorative lines.
09 - Cut into 16 evenly sized bars using a sharp knife and serve chilled.