To make the crust:
Combine the crumbs and butter, and press into the bottom of a 9-inch springform pan.
Bake at 350F for 10 min.
To make the filling:
Blend cream cheese and sugar in the food processor. Add eggs, one at a time, mixing well after each addition. Add vanilla.
Remove 1/2 of the batter to another bowl and stir melted white chocolate and liquer into this.
Blend melted semi-sweet chocolate into remaining batter.
Pour semi-sweet chocolate batter into the crumb-lined pan and spread evenly.
Gently spoon white chocolate batter strategically on the dark chocolate, in dollops. Using the tip of a knife, draw lines through the batter, about 4 to 6 vertically and horizontally, moving alternately right to left, left to right, then down to up and up to down. Take care to do this sparingly; you want to create a marbled effect, not stir the two mixtures together.
Bake at 425F for 10 min. Reduce heat to 250F; bake for 30-35 min. longer or until center of cake is just barely firm.
Remove from oven and run knife around sides.
Allow to cool completely before removing sides.
Melt the 8 squares semi-sweet chocolate with oil and butter over hot water, stirring until smooth.
Place cake on rack over waxed paper. Pour glaze over the entire cake.
Gently shake rack several times to smooth.