Combine chocolate chips and 1/2 cup whipping cream in a medium-sized microwave safe bowl. Microwave on HIGH (100%) 1 to 2 minutes or until melted and smooth, stirring every 30 seconds. Stir in remaining peppermint extract.
Chill chocolate mixture in an ice water bath, stirring frequently until chocolate is cooled to room temperature.
Beat remaining 1 cup whipping cream on high speed of electric mixer, gradually adding powdered sugar, until soft peaks form. Stir in 1/3 of the whipped cream into chocolate mixture. Gently fold in remaining whipped cream; spoon into crust.
Cover and refrigerate 2 to 3 hours or until set. If desired, garnish with additional whipped cream, chocolate sprinkles or fresh berries.