Line an 8-inch square baking pan with foil, extending foil over edges of pan.

Combine sugar, evaporated milk, butter, and salt in a medium, heavy-duty saucepan. Bring to a full rolling boil over medium heat, stirring constantly.

Boil, stirring constantly, for 4 to 5 minutes. Remove from heat.

Stir in marshmallows, chocolate chips, nuts, and vanilla extract. Stir vigorously for 1 minute or until marshmallows are melted.

Pour into prepared baking pan; refrigerate for 2 hours or until firm.

Lift from pan; remove foil. Cut into 48 pieces.