CRUST: * 10 whole graham crackers, broken into pieces * 1 1/4 c. pecans, about 5 oz. * 1/4 c. Sugar * 6 tbsp. (3/4 stick) unsalted butter, melted FILLING: * 1 1/2 lbs. cream Cheese, room temperature * 3/4 c. Sugar * 3 lg. eggs * 1/3 c. Bailey's Irish cream liqueur * 1 tsp. vanilla * 3 oz. white chocolate morsels (Nestle's) TOPPING: * 1 1/2 c. sour cream * 1/4 c. powdered sugar * 1 1/2 oz. white chocolate, chopped or grated * 24 pecan halves *