Preheat your oven to 350°F (175°C). In a mixing bowl, blend together the graham cracker crumbs, granulated sugar, and melted unsalted butter until evenly combined. Press this mixture firmly into the bottom and up the sides of a 9-inch pie dish. Bake for 8-10 minutes, or until the crust is golden and fragrant. Allow it to cool completely.

In a medium saucepan, whisk together the granulated sugar, cornstarch, all-purpose flour, and salt. Gradually whisk in the water and cook over medium heat, stirring constantly, until the mixture thickens and bubbles—about 5-7 minutes. Temper the egg yolks by gradually adding a small amount of the hot mixture to them, then mix it back into the saucepan. Cook for another 1-2 minutes, then stir in the butter, lemon zest, and fresh lemon juice. Pour the filling into the cooled crust and chill in the refrigerator for at least 30 minutes.

While the lemon filling is chilling, prepare the cream layer by beating the cream cheese with powdered sugar and vanilla extract until smooth and creamy. Add in the heavy whipping cream and continue to beat until the mixture forms soft peaks, about 2-3 minutes. Once the lemon filling is set, gently spread the cream mixture over the top.

Cover the pie with plastic wrap and refrigerate for a minimum of 4 hours, or ideally overnight. When ready to serve, garnish with additional whipped cream and lemon slices.