Heat the sweetened condensed milk, bittersweet and semisweet chocolates and the vanilla in a double boiler over medium-low heat until the chocolate is melted. Stir; the mixture will have a slight marshmallow texture. Remove from the heat, cover and refrigerate until chilled, 2 hours.
Roll the chilled mixture in balls, then roll in the melted milk chocolate to coat. Sprinkle with the chipotle salt.
Chipotle salt is sold in specialty stores.
Recipe courtesy of Ree Drummond