Combine cream cheese and margarine, mixing until well blended.
Add flour; mix well.
Divide dough into quarters; divide each quarter into 12 balls.
Press each ball onto bottom and sides of miniature muffin pans.
Combine eggs, brown sugar and vanilla; stir in pecans.
Spoon into pastry shells, filling each cup.
Bake at 325°, 30 minutes or until pastry is golden brown.
Cool 5 minutes, remove from pans.
Sprinkle with powdered sugar, if desired