Put eggs, sugar, vanilla, sour cream and orange and lemon rinds into the blender and cover. Blend on high for 15 seconds. With blender still running, gradually add pieces of cream cheese with melted butter. Blend until smooth. Stop blender to push down with spatula if necessary. Pour cheese mixture into graham cracker crust and bake in preheated oven at 325° for 35 minutes, or until set in center. Turn off heat and leave in oven for another 15 minutes. Remove and cool on rack. When cool, chill in refrigerator for 2 hours before serving. Even better when chilled overnight!!