Peanut Butter Pie

1 baked pie shell or graham cracker shell
1 pint whipped topping
1 8 ounce package cream cheese
1/2 to 3/4 cup sugar ( I use Splenda)
1 cup peanut butter, smooth or chunky
1 teaspoon vanilla

In a mixing bowl, soften cream cheese to room temperature. Stir and blend in peanut butter, sugar and vanilla. Fold in whipped topping until mixture is smooth. Spread into pie shell and refrigerate before serving.