Line an 8-inch square pan with aluminum foil or waxed paper.
Combine marshmallow creme, sugar, evaporated milk, butter, and salt together in a saucepan and bring to a boil. Cook for exactly 5 minutes, stirring constantly. Remove from heat; stir in milk chocolate chips and semisweet chocolate chips until chocolate is melted and mixture is smooth.
Fold cashews and dried cranberries into the chocolate mixture; stir in vanilla extract. Pour mixture into the prepared pan. Cool at room temperature or in the refrigerator until firm, 2 hours. Cut into 1-inch squares.