01 - Preheat oven to 350°F (175°C).
02 - In a mixing bowl, blend graham cracker crumbs, granulated sugar, and melted butter until combined. Firmly press mixture into base and up the sides of a 9-inch pie dish.
03 - Bake crust for 8 to 10 minutes until lightly golden. Remove from oven and allow to cool completely.
04 - In a large bowl, beat softened cream cheese until smooth. Add powdered sugar, sour cream, and vanilla extract, then beat until mixture is fully blended.
05 - In a separate bowl, whip cold heavy whipping cream to stiff peaks. Gently fold whipped cream into the cream cheese mixture until smooth and uniform.
06 - Divide filling evenly into three parts. Leave one plain, color one part with red gel food coloring, and another with blue gel food coloring, blending each until the color is consistent.
07 - Drop alternating spoonfuls of red, white, and blue filling onto the cooled crust. With a skewer or knife, gently swirl the colors together to form a marbled effect, avoiding overmixing.
08 - Smooth surface and refrigerate for at least 2 hours, or until the filling is completely set.
09 - Before serving, spread whipped cream over the top and decorate with fresh strawberry halves and blueberries as desired.