Prepare the Lemon Filling:

1. Whip the Heavy Cream: In a large mixing bowl, use an electric mixer to beat the heavy cream until it forms soft peaks. Set aside.
2. Mix the Pudding: In another bowl, whisk together the instant lemon pudding mix and cold milk until it begins to thicken (about 2 minutes).
3. Add Cream Cheese and Sugar: In a separate bowl, beat the softened cream cheese with powdered sugar and vanilla extract until smooth and creamy.
4. Combine: Gently fold the whipped cream into the pudding mixture, then add the lemon juice and lemon zest, stirring until fully incorporated. Set aside.

Assemble the Cake:

5. Layer the Graham Crackers: In a 9×13-inch baking dish, arrange a layer of graham crackers to cover the bottom of the dish.
6. Add the Lemon Filling: Spread half of the lemon filling mixture over the graham crackers, smoothing it into an even layer.
7. Repeat the Layers: Place another layer of graham crackers on top of the filling, followed by the remaining lemon filling. Smooth the top layer to cover evenly.

Prepare the Lemon Glaze:

8. Make the Glaze: In a small bowl, whisk together the fresh lemon juice and powdered sugar until smooth. Drizzle the glaze over the top of the cake, spreading it gently with a spatula.

Chill and Serve:

9. Chill the Cake: Cover the dish with plastic wrap and refrigerate for at least 3.5 hours or until the cake has set and the layers are firm.
10. Serve: Once chilled, slice into squares and serve. Garnish with extra lemon zest or a few fresh berries, if desired.