Prep a 9×13 inch rectangular baking dish. Line with parchment paper, leaving some overhang for easy lifting.
In a large bowl, mix graham cracker crumbs with softened butter until crumbly and moist.
Press the crumb mixture firmly into the prepared dish, using a rolling pin to create an even layer of crust.
In a separate bowl, beat cream cheese with sugar and vanilla until smooth and creamy.
Spread the cream cheese mixture evenly over the crust layer.
Chill in refrigerator for at least 1 hour or until firm.
In a large bowl, beat heavy whipping cream with powdered sugar and vanilla until soft peaks form.
Spread the whipped cream evenly over the cream cheese layer.
Chill again for at least 1 hour or until firm.
Carefully spread the strawberry pie filling evenly over the whipped cream layer in one side of the dish.
Spread the blueberry pie filling on the opposite side, leaving a white whipped cream strip in the center to form a red-white-blue pattern.
Chill for at least 2 hours before serving.
Garnish with fresh mixed berries just before serving.