Place a greased 9-in. springform pan on a double thickness of heavy-duty foil (about 18 in. square). Securely wrap foil around pan. , In a small bowl, combine the cracker crumbs, sugar and butter. Press onto the bottom of pan. Place on a baking sheet. Bake at 325° for 10 minutes. Cool on a wire rack., In a large bowl, beat the cream cheese, sugar and flour until smooth. Add eggs; beat on low speed just until combined. Gradually stir in the eggnog, extract and nutmeg. Pour filling over crust., Place springform pan in a larger baking pan; add 1 in. of hot water to larger pan. , Bake at 325° until center is just set and top appears dull, 45-50 minutes. Remove springform pan from water bath. Cool on a wire rack for 10 minutes. Loosen sides from pan with a knife; cool 1 hour longer. Refrigerate overnight, covering when completely cooled. If desired, top with whipped cream, then sprinkle with nutmeg.