Creamy Key Lime Pie

14- ounce can sweetened condensed milk
8-ounce package cream cheese, softened
½ cup lime juice
½ teaspoon vanilla
9-inch graham cracker crust
Optional: frozen whipped topping, thawed
Optional: 1-2 drops green food coloring

In a bowl, beat condensed milk, cream cheese and lime juice; blend until smooth. Stir in vanilla; pour into pie crust. Cover and chill for at least 3 to 4 hours. Top with Whipped topping if desired.