Cut 3 cm crosswise off of each cooky. Crush the short pieces; set long ones aside for a garnish. Mix the cooky crumbs, Graham cracker crumbs, & the butter. Press this mixture firmly into the bottom of a 23 cm springform pan. Beat the cream cheese in a large bowl until smooth. Gradually add 1 cup of eggnog, blending until smooth. Add remaining eggnog, buttermilk, pudding mix, rum, & nutmeg. Deat until well blended. Pour carefully into the springform pan. Chill until firm, usually approx. 3 hours. Remove the sides of the pan. Place the remaining cooky pieces on top as a garnish then top with the whipped cream. Serves 10-12. Enjoy!