Preheat your oven to 350°F (175°C). In a mixing bowl, combine graham cracker crumbs, granulated sugar, and melted unsalted butter until well blended. Press the mixture firmly into a 9-inch pie dish to form an even layer. Bake for 8-10 minutes, or until lightly golden and fragrant. Allow it to cool completely.

In a medium saucepan, whisk together granulated sugar, cornstarch, all-purpose flour, and salt over medium heat. Gradually add water, stirring constantly until the mixture thickens and begins to bubble, about 5-7 minutes. Carefully temper the egg yolks and pour them into the pan. Cook for an additional 2-3 minutes, then stir in butter, lemon zest, and fresh lemon juice until smooth.

In a separate mixing bowl, beat softened cream cheese with powdered sugar and vanilla extract until smooth. In another bowl, whip heavy cream to stiff peaks. Gently fold the whipped cream into the cream cheese mixture, then pour it into the cooled crust.

Cover the pie and refrigerate for at least 4 hours. Just before serving, garnish with whipped cream and fresh lemon slices.