Mix sugar, powdered cocoa, salt, milk, and butter together in a medium saucepan. Bring to a boil, start timing when the mixture reaches a full boil, and cook stirring for 1-1/2 minutes.
Remove from heat and stir in peanut butter, vanilla, and oats.
Drop by rounded spoonfuls on wax paper. Allow cookies to cool before eating. Makes about 40 cookies.