Line an 8-inch square pan with parchment or waxed paper, allowing the paper to hang over the sides.
In a medium bowl, stir together the white chocolate chips, the condensed milk, and the salt. Melt the mixture according to the white chocolate package directions, then stir in the vanilla extract and 1 cup of the peppermint candies. Pour the fudge into the prepared pan and use a spatula to spread it evenly. Scatter on the remaining peppermint candy. Chill the fudge in the refrigerator until it's firm and set, about 2 hours. Use the overhanging flaps of paper to lift the fudge from the pan, then slice it into 1-inch squares.