PREPARE CHOCOLATE CRUMB CRUST:

1-2 tbsp. unsalted butter (room temperature)
1 pkg. (8 1/2 oz.) chocolate wafer cookies, finely ground
Pinch of salt
Pinch of cinnamon
1/3 c. unsalted butter, melted & cooled to room temperature

Coat bottom and sides of 9 inch springform pan evenly with unmelted butter. Mix cookie crumbs, salt and cinnamon in medium bowl. Drizzle melted butter over crumb mixture. Stir and toss mixture vigorously with fork until slightly darkened and uniform. Press crumb mixture evenly on sides and bottom of pan. Refrigerate crust 30 minutes.

12 oz. semi-sweet chocolate, broken into sm. pieces
2 tbsp. unsalted butter
1 1/2 lb. cream cheese, room temperature
1 1/2 c. whipping cream
1 tsp. vanilla
1 c. granulated sugar
3 lg. eggs, room temperature, slightly beaten
2 tbsp. unsweetened cocoa powder

Place oven rack in center of oven, 350 degrees. Combine chocolate and butter in top of double boiler; place over hot but not simmering water. Cook over low heat just until chocolate is completely melted. Remove top of double boiler from water; stir chocolate mixture until smooth. Reserve at room temperature, uncovered.

Cut cream cheese into 1 inch cubes; place in large mixer bowl. Beat at medium speed, scraping sides as needed, until completely smooth. Gradually beat in chocolate mixture. Beat until smooth and uniformly colored. Continue beating while gradually adding cream and vanilla.

Continue beating cheese mixture at medium speed while very slowly adding granulated sugar. Add eggs, about 1/4 cup at a time. Beat well after each addition. Sieve cocoa powder over batter; beat at low speed until cocoa is blended.

Pour batter into cold unbaked chocolate crumb crust; spread top smooth. Gently rotate pan several 1/4 turns to settle batter. Bake 30 minutes. Reduce oven to 325 degrees and bake 30 minutes longer. Turn off heat. Let cake stand in oven with door ajar 30 minutes. Transfer pan to wire rack away from drafts. Let cool to room temperature.

Remove sides of pan. Refrigerate overnight or at least 8 hours. Just before serving sieve powdered sugar lightly over cake.