Mix together sugar, cocoa powder, and salt in a saucepan. Stir in milk and butter. Turn heat to medium and bring to a boil. Cook for 1 1/2 minutes. Remove from heat.
Stir the hot mixture continuously while adding flaked coconut, quick oats, old-fashioned oats, walnuts, peanut butter, and vanilla extract. Mix well. Spoon onto waxed paper-lined cookie sheets and freeze for 3 hours.