01 - Preheat oven to 350°F.
02 - Combine graham cracker crumbs, granulated sugar, and melted butter in a bowl. Press mixture evenly into the bottom and sides of a 9-inch pie dish.
03 - Bake the crust for 8 to 10 minutes until lightly golden. Remove from oven and allow to cool completely.
04 - Beat softened cream cheese until smooth in a large bowl. Incorporate powdered sugar, sour cream, and vanilla extract; mix until thoroughly blended.
05 - Whip cold heavy whipping cream in a separate bowl to stiff peaks.
06 - Gently fold the whipped cream into the cream cheese mixture until smooth and uniform.
07 - Divide the filling equally into three portions. Leave one plain, tint one with red gel food coloring, and tint the last portion with blue gel food coloring. Mix each until color is evenly distributed.
08 - Drop spoonfuls of the white, red, and blue fillings randomly on the cooled crust. Swirl gently with a skewer or knife to create a marbled effect. Avoid overmixing.
09 - Smooth the top of the pie. Refrigerate for at least 2 hours, or until the filling is completely set.
10 - Before serving, garnish with whipped cream and arrange fresh strawberries and blueberries as desired.