01 - Preheat oven to 350°F (175°C).
02 - In a mixing bowl, combine graham cracker crumbs, granulated sugar, and melted butter. Press mixture evenly onto the bottom and 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 cream cheese with an electric mixer until smooth. Add powdered sugar, sour cream, and vanilla extract. Beat until well combined.
05 - In a separate bowl, whip cold heavy whipping cream to stiff peaks. Gently fold whipped cream into the cream cheese mixture until well incorporated and smooth.
06 - Divide filling evenly into three bowls. Leave one portion plain (white). Add red gel food coloring to one bowl and blue gel food coloring to another, mixing each until the desired vibrant color is achieved.
07 - Drop spoonfuls of each colored filling alternately onto the cooled crust. Use a skewer or knife to gently swirl the colors to create a marbled effect, avoiding overmixing.
08 - Smooth the surface with a spatula. Refrigerate for a minimum of 2 hours or until the filling is completely set.
09 - Before serving, top with whipped cream and arrange fresh strawberries and blueberries as desired.