01 - Set oven temperature to 350°F (175°C).
02 - In a mixing bowl, combine graham cracker crumbs, granulated sugar, and melted butter. Mix thoroughly and firmly press the mixture into the base and up the sides of a 9-inch pie dish.
03 - Bake crust in preheated oven for 8 to 10 minutes until lightly golden. Remove from oven and allow to cool completely on a wire rack.
04 - In a large bowl, beat softened cream cheese until smooth. Add powdered sugar, sour cream, and vanilla extract; beat until uniform and creamy.
05 - In a separate bowl, whip cold heavy cream with an electric mixer until stiff peaks form.
06 - Gently fold whipped cream into the cream cheese mixture until fully combined and smooth.
07 - Separate the filling into three equal portions. Leave one portion plain, tint one with red gel food coloring, and tint the remaining portion with blue gel food coloring. Mix each portion until the color is even.
08 - Place spoonfuls of the red, white, and blue fillings randomly onto the cooled crust. Using a skewer or knife, gently swirl colors together to create a marbled pattern, without overmixing.
09 - Smooth the pie surface with a spatula. Refrigerate for at least 2 hours, or until the filling is fully set.
10 - Prior to serving, pipe whipped cream over the top and arrange fresh strawberries and blueberries as desired.