1. For crust: preheat oven to 325°F.

2. Lightly butter 9-inch diameter springform pan with 2 ¾-inch-high sides.

3. Finely grind graham crackers, pecans and sugar in processor.

4. Add butter and blend, using on/off turns.

5. Press crumbs onto bottom and 2 inches up sides of prepared pan. Refrigerate 20 minutes.

6. For filling: using electric mixer, beat cream cheese and sugar in large bowl until smooth.

7. Whisk eggs, baileys and vanilla in medium bowl until just blended.

8. Beat egg mixture into cream cheese mixture.

9. Finely chop white chocolate in processor using on/off turns.

10. Add to cream cheese mixture.

11. Transfer filling to crust-lined pan. Bake until edges of filling are puffed and dry looking and center is just set, about 50 minutes.

12. Cool on rack.

13. For topping: mix sour cream and powdered sugar in small bowl.

14. Spread topping onto cooled cake.

15. Refrigerate until well chilled, about 6 hours.

16. (can be prepared 1 day ahead).

17. Sprinkle grated chocolate over cake.

18. Place pecans around edge and serve.

19. Note: i"ve fixed the cake with and without the topping, and i prefer it without the topping.

20. As a suggestion, prepare the topping, but serve it on the side.