Combine the chocolate chips & sweetened condensed milk in a saucepan. Cook, while stirring, on medium heat until melted. Divide, and distribute equally between the 2 prepared pie crusts.
Beat together the cream cheese and confectioners sugar until creamy. Mix in the peanut butter, milk, & vanilla & beat until smooth. Fold in the whipped topping.
Divide the filling between the two pie crusts. Drizzle with (warm) hot fudge topping, if desired. Freeze until firm.