For the filling: Whisk
, eggs, confectioners' sugar, cornstarch, and salt in a medium saucepan
. Cook over medium heat, whisking constantly, until boiling. Continue to cook until the consistency of mayonnaise
, about 2 minutes more. Transfer to a bowl. Whisk in the cream cheese, peanut butter, and vanilla. Spread evenly over the chocolate and refrigerate until cold or overnight.