In a large bowl, cream butter and sugar. Add melted chips; mix well. Add eggs, one at a time, beating well after each addition. Beat in vanilla. Combine the flour, baking soda, baking powder and salt; add to creamed mixture alternately with milk.
Pour into two greased and floured 9-in. round baking pans. Bake at 350° for 25-30 minutes or until a toothpick inserted in the center comes out clean. Cool for 10 minutes before removing from pans to wire racks to cool completely.
For frosting, in a small bowl, beat the melted chips, cream cheese, vanilla and salt until light and fluffy. Beat in confectioners' sugar and milk. Spread frosting between layers and over top and sides of cake. Store in the refrigerator.