Make the crust: Preheat oven to 375F. Combine crumbs, butter and sugar and stir together. Press mixture into the bottom of a 9-inch round springform pan and bake for about 10 minutes. Cool completely before filling.
Heat oven to 325 F and get out a large roasting pan that will fit the springform pan. Cover the sides and bottom of the springform pan very, very well with aluminum foil.
In a food processor, blend sugar and cream cheese until smooth. Add in vanilla extract and the eggs, one at a time, until blended and smooth. Add in mascarpone and process again. Pour into the crust and place in roasting pan.
Place the pan in the oven and fill halfway up the sides of the springform with warm water.
Bake for 55 minutes at 325. Turn off the oven and leave the cake inside for 45 minutes, until the center just seems set but will still ripple when the pan is jiggled.
Remove from water bath and cool compeletely on a wire rack. When it has cooled, refrigerate overnight or until cold, before serving.