01 - Set oven to 350°F and allow to fully preheat before assembling the crust.
02 - In a mixing bowl, combine graham cracker crumbs, granulated sugar, and melted butter until evenly moistened. Press mixture firmly and evenly into the bottom and up the sides of a 9-inch pie dish.
03 - Place the pie dish on the center rack and bake for 8 to 10 minutes until the crust turns lightly golden. Remove from the oven and let cool completely.
04 - Using an electric mixer, beat softened cream cheese until smooth. Add powdered sugar, sour cream, and vanilla extract; continue to beat until the mixture is fully incorporated and creamy.
05 - In a clean bowl, whip heavy cream on high speed until stiff peaks form. Gently fold the whipped cream into the cream cheese mixture, blending until the filling is smooth and airy.
06 - Portion the filling evenly into three bowls. Leave one part uncolored (white), tint the second part with red gel food coloring, and tint the third part with blue gel food coloring. Mix each until the color is consistent.
07 - Spoon dollops of the red, white, and blue fillings in a random pattern over the cooled crust. Use a skewer or knife to gently swirl the colors together for a marbled appearance, avoiding overmixing.
08 - Smooth the top with a spatula. Refrigerate for at least 2 hours, or until the filling is fully set and firm.
09 - Before serving, pipe or spoon whipped cream over the surface. Garnish with halved strawberries and fresh blueberries as desired.