In a bowl, mix graham cracker crumbs and melted butter until it resembles wet sand.
Press the crumb mixture firmly into the bottom and up the sides of a 9-inch tart pan. Freeze for 15 minutes.
In a large bowl, beat the softened cream cheese and granulated sugar together until completely smooth and fluffy (about 3-4 minutes).
Mix in the fresh lemon juice and lemon zest until just combined. Do not overmix.
Pour the filling into the chilled crust and smooth the top. Chill in the refrigerator for at least 6 hours, or overnight, until set. Serve cold.
