Combine gingersnap crumbs and melted butter; stir well. Press crumb mixture into bottom and 1" up sides of a 10" springform pan. Bake at 350° for 10 minutes. Let cool. Reduce oven temperature to 300°.
Bring whipping cream to a simmer in a saucepan. Remove from heat and pour over chocolate in a large bowl. Stir mixture with a rubber spatula until smooth. Let cool.
Beat cream cheese at high speed of an electric mixer until creamy. Add sugar; beat well. Add eggs, one at a time, beating after each addition. Fold in chocolate mixture. Stir in vanilla. Pour batter into prepared crust.
Bake at 300° for 1 hour and 15 minutes. Let cool completely on a wire rack. Cover and chill at least 8 hours. Remove sides of pan. If desired, decorate cheesecake with Candied Cranberries and Pistachio Crunch.