Chocolate Mousse Pie

1 Keebler Ready-Crust Graham Cracker pie crust
1-1/2 cups milk
1 envelope unflavored gelatin
1 package (6 oz) semi-sweet chocolate chips
1 teaspoon vanilla
2 cups whipped topping

In saucepan, sprinkle unflavored gelatin over milk. Let stand 1 minute. Stir over low heat until gelatin is completely dissolved, about 5 minutes. Add chocolate and continue cooking, stirring constantly until chocolate is melted; stir in vanilla. Chill 1 hour, stirring occasionally, until mixture mounds when dropped from spoon. Fold in whipped topping. Turn into crust and chill 3 to 4 hours.