Preheat the oven to 350℉. Spray the bottom of a 9x9-inch pan with nonstick spray.
MAKE THE CRUST:
In a medium bowl, combine the graham cracker crumbs, sugar and butter. Press the crust into the bottom of the prepared pan, and bake for 8 minutes. Let the crust cool while you prepare the filling.
MAKE THE FILLING:
In a large bowl, use an electric mixer to beat the cream cheese until smooth. Gradually add the condensed milk and continue beating until smooth. Add the lemon juice and vanilla, and beat until combined. Pour this mixture over the cooled crust. Gently spoon the blueberry pie filling over the cream cheese mixture. Layer the whipped topping over the pie filling one spoonful at a time, gently spreading as you go to avoid smearing pie filling into the topping. Refrigerate for at least a few hours before cutting and serving.