Grease 8-inch square baking dish; line with 8-by-14-inch sheet parchment, letting excess hang over. In saucepan, cook condensed milk, chocolate and salt over medium, stirring until smooth, about 5 minutes. Pour half of chocolate mixture into pan. Sprinkle with half of raisins, almonds, pretzels and marshmallows. Spoon and spread remaining chocolate mixture on top. Sprinkle with remaining raisins, almonds, pretzels and marshmallows; pat to stick. Refrigerate 1 hour. Using parchment, lift fudge from pan; cut into squares.