Line one 9x13 inch pan with aluminum foil sprayed with non-stick spray. In a microwave safe bowl, combine the chocolate chips, butterscotch or peanut butter chips, condensed milk and salt. Microwave on high for 2 minutes. Remove, stir, and heat on high for 1 to 2 minutes longer. Remove and still until all chips are melted. Add vanilla and mix well; pour into prepared pan. Chill refrigerator overnight, or until set. Remove foil, slice and serve.