Prepare the Crust:
In a medium bowl, combine graham cracker crumbs, sugar, and melted butter. Mix well until the crumbs are coated in butter. Press the mixture evenly into the bottom of an 8×8-inch or 9×9-inch square baking dish. Use the back of a spoon to pack it down firmly. Refrigerate while you prepare the filling.

Make the Lemon Cream Filling:
In a large mixing bowl, beat the softened cream cheese with an electric mixer until smooth and creamy. Add the sweetened condensed milk, fresh lemon juice, lemon zest, and vanilla extract. Beat until fully combined and smooth.

Whip the Cream:
In a separate bowl, whip the heavy cream until stiff peaks form. Gently fold the whipped cream into the lemon mixture, being careful not to deflate the whipped cream.

Assemble the Bars:
Spread the lemon cream mixture over the chilled graham cracker crust, smoothing the top with a spatula.

Chill and Set:
Refrigerate the lemon cream pie bars for at least 4 hours, or overnight, to allow them to set properly.

Serve:
Once the bars have set, slice into squares and serve. Optionally, garnish with extra lemon zest or whipped cream before serving.