Preheat your oven to 350°F (175°C). In a medium bowl, combine the graham cracker crumbs, granulated sugar, and melted unsalted butter until well mixed. Press this mixture firmly into the bottom and up the sides of a pie plate to form an even crust. Bake for 8-10 minutes, or until lightly golden, then remove from the oven and allow it to cool completely.

In a medium saucepan, whisk together the granulated sugar, cornstarch, and a pinch of salt. Gradually add 1 cup of water, continuously stirring as you cook over medium heat until the mixture thickens and bubbles, about 5-7 minutes. Carefully temper the egg yolks, and return it to the saucepan, cooking for an additional 1-2 minutes until slightly thickened. Stir in the butter and fresh lemon juice until smooth. Pour the filling into the cooled crust and set aside to chill for 30 minutes.

In a large bowl, beat the softened cream cheese, powdered sugar, and vanilla extract together until smooth. In a separate bowl, whip the heavy cream until stiff peaks form, then gently fold it into the cream cheese mixture. Spread this cream layer over the chilled lemon filling.

Cover the pie with plastic wrap, pressing it against the surface to prevent a skin from forming. Refrigerate the Lemon Supreme Pie for at least 4 hours, or ideally overnight, to allow the flavors to meld and the filling to set properly. When ready to serve, slice the pie and garnish with whipped cream or fresh lemon slices.