In a medium bowl, combine the graham cracker crumbs and melted butter. Mix until the crumbs are well coated. Press the mixture into the bottom of a 9x13-inch baking dish to form a crust. Refrigerate for 10 minutes to set.
In a large bowl, beat together the softened cream cheese and powdered sugar until smooth. Add the vanilla extract and mix until well combined.
Gently fold in 1 cup of the whipped topping into the cream cheese mixture until fully incorporated. Spread this mixture evenly over the chilled graham cracker crust.
Layer the mixed berries over the cream cheese layer, spreading them out evenly.
Spoon the berry pie filling over the berries, spreading it gently to cover.
Top with the remaining whipped topping, spreading it evenly over the pie filling.
If using, sprinkle sliced almonds on top for added crunch.
Cover the dish with plastic wrap and refrigerate for at least 4 hours, or overnight for best results.
Before serving, slice into squares and enjoy!