PREPARATION:

1. Butter 13X9-inch pan; set aside. Lightly butter side of heavy, large saucepan.
2. Combine evaporated milk, both chips, marshmallow creme, butter, sugar and salt in prepared saucepan. Cook over medium heat, stirring constantly, until sugar dissolves and mixture comes to a boil. Wash down side of pan with pastry brush frequently dipped in hot water to remove sugar crystals.
3. Add candy thermometer. Stir mixture occasionally. Continue to cook until mixture reaches the soft-ball stage (238°F).
4. Pour into large heat-proof mixer bowl. Cool to lukewarm (about 110°F).
5. Add vanilla and beat with heavy-duty electric mixer until thick. Beat in 1 cup of the chopped pecans when candy starts to lose its gloss. Immediately spread in prepared pan. Sprinkle remaining chopped pecans over fudge; gently press into fudge. Score fudge into squares with knife. Refrigerate until firm.
6. Cut into squares. Store in refrigerator.