In a small bowl, cream butter and cream cheese. Beat in butter flavoring. Gradually add flour until mixture forms a ball. Cover and refrigerate for 20 minutes or until easy to handle.
Roll out pastry to fit a 9-in. pie plate. Place pastry in plate; trim to 1/2 in. beyond edge of plate. Flute edges. Place pecans in crust; set aside.
In a small bowl, combine brown sugar and flour. Add the remaining ingredients; beat until combined. Pour over pecans. Bake at 350° for 45-50 minutes or until a knife inserted in the center comes out clean. Cool completely on a wire rack. Refrigerate leftovers.