In a large bowl, combine the milk chocolate, semi-sweet chocolate, butter, marshmallow cream and nuts.
In a large saucepan over medium heat, combine the evaporated milk and sugar. Stir constantly and bring to a boil for 4 minutes.
Pour hot sugar mixture over chocolate mixture and stir with large spoon until well blended (do this quickly before fudge begins to harden). Once this is well blended, pour fudge into a buttered 9x13 inch baking pan. Spread out and smooth into pan.
Set aside to cool and harden, about 6 hours. Cut into squares when ready to serve.