Preheat oven to 325°. In a large bowl, combine the graham cracker crumbs, pecans, sugar and butter; set aside 1/3 cup for topping. Press remaining crumb mixture onto the bottom and 1 in. up the sides of a greased 9-in. springform pan., Place springform pan on a double thickness of heavy-duty foil (about 18 in. square). Securely wrap foil around pan., In a large bowl, beat cream cheese and sugar until smooth. Beat in the sour cream, vanilla and butter flavoring. Add eggs; beat on low speed just until combined. Fold in pecans. Pour into crust; sprinkle with reserved crumb mixture. Place springform pan in a large baking pan; add 1 in. of hot water to larger pan., Bake until center is almost set, 70-80 minutes. Remove springform pan from water bath. Cool on a wire rack for 10 minutes. Carefully run a knife around edge of pan to loosen; cool 1 hour longer. Refrigerate overnight, covering when completely cooled. Remove sides of pan.