In a medium bowl, combine graham cracker crumbs and melted butter. Mix until well combined. Press the mixture firmly into the bottom of a 9x13 inch baking dish to form the crust.
In a large mixing bowl, beat the softened cream cheese and powdered sugar together until smooth and creamy.
In another bowl, whip the heavy cream and vanilla extract until stiff peaks form. Gently fold the whipped cream into the cream cheese mixture until fully combined.
Spread the cream cheese mixture evenly over the graham cracker crust in the baking dish.
Layer the mixed berries over the cream cheese layer, pressing them gently into the mixture.
Spread the whipped topping evenly over the berries.
Cover the dish with plastic wrap and refrigerate for at least 4 hours, or overnight for best results.
Before serving, garnish with additional berries if desired. Cut into squares and enjoy!