Line 8-inch square baking pan with heavy duty foil. Lightly butter foil.
Combine sugar, evaporated milk, butter and salt in medium, heavy-duty saucepan. Bring to a full rolling boil over medium heat, stirring constantly. Boil, stirring constantly for 4 1/2 to 5 minutes. Remove from heat.
Stir in marshmallows, white chocolate chips, nuts and maple syrup or maple extract. Stir vigorously for 1 minute or until marshmallows are melted. Pour into prepared baking pan. Refrigerate until firm. Lift from pan; remove foil. Cut into squares.