Combine first 4 ingredients; stir well. Firmly press onto bottom and 2 1/2" up sides of a lightly greased 7" springform pan. Bake at 350° for 8 minutes. Remove to a wire rack; let cool. Reduce oven temperature to 300°.
Combine chocolate squares and 3/4 cup butter in a heavy saucepan. Cook over medium-low heat until mixture is melted and smooth, stirring frequently. Remove from heat and let cool.
Beat cream cheese at medium speed of an electric mixer until creamy. Add 3/4 cup sugar; beat well. Add eggs, one at a time, beating after each addition. Stir in cooled chocolate mixture. Pour into prepared crust.
Bake at 300° for 50 minutes to 1 hour or until almost set. Turn oven off. Let cheesecake cool in oven 30 minutes. Remove to a wire rack; let cool to room temperature.
Remove sides of pan. Serve cheesecake with Hot Fudge Sauce. Garnish, if desired.