In a medium bowl combine walnuts, apricots, and raisins. Remove 1/4 cup to sprinkle on top of fudge. Line a 13x9x2-inch baking pan with foil, extending foil over edges of pan. Butter the foil; set pan aside.
Butter sides of a heavy 3-quart saucepan. In saucepan combine sugar, sour cream, and butter. Cook and stir over medium heat until mixture boils. Clip a candy thermometer to side of pan. Reduce heat to medium-low; continue boiling at a moderate, steady rate, stirring occasionally, until thermometer registers 236 degrees F (18 to 20 minutes). Adjust heat as necessary to maintain a steady boil.
Remove saucepan from heat. Stir in white chocolate and marshmallow creme. Continue stirring until chocolate is melted and mixture is combined. Stir in fruit and nut mixture. Immediately spread fudge evenly in prepared pan. Top with the reserved 1/4 cup fruit and nut mixture. Chill fudge until firm. Use foil to lift fudge out of pan. Cut fudge into squares. Store in the refrigerator.