In a mixing bowl, beat the softened cream cheese with an electric mixer until smooth and creamy, about 2 minutes.

Gradually add the sifted powdered sugar, mixing until fully incorporated.

Add the fresh lemon juice, lemon zest, and vanilla extract. Mix until well combined.

In a separate bowl, whip the chilled heavy cream until stiff peaks form. This will give the cake a light and airy texture.

Gently fold the whipped cream into the lemon cream mixture using a rubber spatula until no streaks remain.

In a medium bowl, combine the fresh blueberries, granulated sugar, and lemon juice. Toss gently to coat the blueberries and let sit for about 10 minutes to release their juices.

In a separate bowl, combine the graham cracker crumbs and melted butter. Mix until the crumbs are evenly coated.

Pour the milk into a shallow dish. Quickly dip each graham cracker sheet into the milk, ensuring they are soaked but not falling apart.

In the bottom of a 9x13 inch baking dish, layer half of the soaked graham crackers.

Spread half of the lemon cream mixture over the graham crackers, smoothing it out evenly.

Layer half of the blueberry mixture over the lemon cream.

Repeat the layers with the remaining soaked graham crackers, lemon cream, and blueberries.

Cover the dish with plastic wrap and refrigerate for at least 4 hours, or overnight, to allow the flavors to meld and the cake to set.

Once set, slice the icebox cake into squares and serve chilled. Garnish with additional blueberries and lemon zest if desired.