For crust: Preheat oven to 325 degrees F. Butter 10-inch-diameter spring form pans with 2¾-inch-high sides. Wrap outside of pan with heavy-duty aluminum foil.
Place cookies and pecan pieces in processor and blend until coarse crumbs form. Add butter and process until evenly moistened. Press crumb mixture firmly onto bottom of prepared pan. Bake crust 5 to 7 minutes; cool on rack.
For filling: Steam Kabocha squash, press through sieve. Measure 5 ounces puree and set aside.
Using electric mixer beat cream cheese and sugar in large bowl until smooth. Beat in eggs, 1 at a time until just blended. Stir in zests, vanilla and grand Marnier. Transfer 2 cups of batter to medium bowl; stir in Kabocha puree. Stir reserved batter with chocolate chunks.
Pour white chocolate mixture batter into prepared pan and spoon Kabocha mixture onto white chocolate mixture and swirl with back of spoon.
Place spring form pans in large roasting pan. Pour enough hot water into roasting pan to come 1 inch up sides of pan. Bake uncovered until filling is puffed around edges and moves slightly in center when pan is gently shaken, about 1 hour.
Remove pans from water; remove foil; cool slightly. Refrigerate cake at least 4 hours. (Can be prepared 2 days ahead; cover and keep refrigerated.)
Run small knife around pan sides to release cheesecake from the pan. Garnish cheesecake with large white chocolate curls, if desired.
Notes
Chef's note: Left over cheesecake batter can be saved in the refrigerator for 3 to 4 days; drop onto brownie or muffin batter for added finesse.
Recipe by Webicurean at http://blog.webicurean.com/2006/10/10/white-chocolate-kabocha-pumpkin-cheesecake/