Combine crumbs and butter; press firmly on bottom of a 9-inch spring form pan.

In a large mixing bowl or food processor, beat cream cheese until fluffy. Gradually beat in sweetened condensed milk until smooth. Add eggs; mix well. Divide batter in half (about 3 cups each); beat cocoa and vanilla into one half. Pour into prepared pan. Stir liqueurs into remaining batter. Spoon evenly over chocolate batter.

Bake at 300 degrees for 1 hour and 10 minutes, or until center is set. Turn off oven and allow cheesecake to cool 1 hour in oven with door open slightly. Remove side of pan. Carefully spread top with chocolate glaze. Chill thoroughly.

In a small saucepan, over low heat, melt chocolate with whipping cream. Cook and stir until thick and smooth. Immediately spread over warm cheesecake.