Bake the pie crust according to the package directions; cool.
Combine 2 cups of the raspberries and 1/2 cup of the sugar in a medium bowl; stir with a fork, crushing the raspberries to blend. Let stand for 15 minutes. Beat the cream cheese, sour cream, remaining 1/4 cup sugar and vanilla in a large bowl at medium speed for 1 minute or until smooth and fluffy. Stir in the raspberry mixture; fold in the whipped topping.
Spoon the filling into the baked pie shell. Freeze for 6 hours or overnight.
Let stand for 20 to 30 minutes at room temperature before serving. Garnish with remaining 1 cup of raspberries.