Blend together the 1/2 cup butter, cream cheese and flour until mixture is smooth and can be shaped into a ball. Cut in half and divide each half into 12 balls. Press each ball over bottom and up sides of tine 1 3/4 inch diameter muffin pans to make a tart shell. Beat egg with brown sugar, remaining tablespoon of butter, vanilla and salt. Stir in raisins, orange peel and walnuts. Spoon into the prepared pans. Bake below oven center at 375 degrees f. for 25 minutes or until browned lightly. Cool in pans.