Place the softened cream cheese into a bowl and blend with a hand mixer (or stand mixer) until smooth. Add the sweetened condensed milk, lemon juice and zest; continue blending until fully combined and completely smooth.
Transfer the filling into the graham crust, smooth the top with an offset spatula and chill until set; about 2 to 4 hours. For crisp, sharp slices, you freeze the pie for 30 minutes or so just before serving.
Top with whipped cream or cool whip and serve chilled.
Notes
Make Ahead: How far in advance can this recipe be made? It's best up to 2 days ahead, but it will keep for up to 5 days. Cover the lemon pie and store it in the refrigerator.
Freezing: Can this Lemon Pie be frozen? Absolutely. Wrap it well and freeze for up to 3 months.