Combine butter, evaporated milk, sugar, and salt in a medium saucepan. Bring to a hard boil for 5 to 7 minutes, stirring constantly. Remove from heat. Stir in the chocolate until melted and smooth. Fold in the almonds and marshmallows. Pour into an 8 by 8-inch square baking pan. Chill until firm, about 2 to 4 hours. Cut into 12 squares.