Reserve 1/2 cup mincemeat.
Spoon remainder into tart shells.
Add cheese to eggs; beat till smooth.
Blend in sour cream, lemon peel, flavoring.
Mix sugar and flour; stir into cheese mixture.
Pour over mincemeat in tarts.
Bake in moderate oven (375°) 25 to 30 minutes or till lightly browned.
Top with reserved mincemeat.